the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 11 Dec 2023
High-resolution reconstruction of drought episodes during the Dalton Solar Minimum (1790–1830) in the Spanish Mediterranean Basin
Abstract. Drought is a common climate risk in the Mediterranean region, but in connection to climate change, its frequency and severity are predicted to increase during the next century. In order to better manage future scenarios in which global warming will be superimposed to natural climate variability, the nature of droughts before industrial times should be analysed in depth. This approach takes into account a broader time scale to the study of severe droughts, allowing the identification of lower frequency droughts that happened before the instrumental period. The objective of this study is to analyse the occurrence and magnitude of the extreme droughts, with durations of more than a year, in Spain during the Dalton Solar Minimum period (1790–1830). To achieve this objective, the study takes into account the use of instrumental observations and information obtained from historical documentary sources from daily to monthly resolution. The results reveal that drought episodes were more frequent and severe during the Dalton Solar Minimum period than during the second half of the nineteenth century. Furthermore, drought episodes of similar severity were hardly seen throughout the twentieth century. Only in the current context of climate change, for the last two decades, a similar pattern of high drought severity has been identified that resembles the severity found during the Dalton Solar Minimum period (especially between 1812 and 1825). This study highlights the presence of a high variability in drought patterns during the last centuries, justifying more efforts of research on drought episodes at high temporal resolution for long time periods.
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RC1: 'Comment on egusphere-2023-2177', Anonymous Referee #1, 04 Jan 2024
The authors present new high-resolution hydrometeorological and climatological data for north-eastern Spain for the period of the late 18th and early 19th centuries. This is important because the authors, who are very experienced in the field of regional historical climatology, provide new insights from reliable and highly relevant documentary evidence, so-called rogations, and place them in the context of today's drought conditions. The topic is therefore suitable for the journal and the reviewer is very much in favour of publishing the article after revision. However, some sections need to be reconsidered and rewritten. Currently, the paper is rather descriptive and speculative and needs more scientific basis and arguments for the conclusions the authors draw.
In addition, the manuscript needs extensive English editing.
Below are some general comments that should be taken into account. They are not in any particular order and should be addressed in addition to the general statements above:
Abstract/conclusions: These sections are rather general and duplicate text from other sections. Both sections need to be refocused when revising the paper.
Introduction: This section should include the drought definitions from the IPCC's latest AR6.
Further, this section and the objectives do not yet provide the reader with the necessary justification as to why this paper is necessary, what has been published on this topic so far and what new elements the authors intend to cover in this publication. These sections therefore need to be better structured and reflect the state of research in this area.
The section on the current state of historical drought research is not complete. The authors also need to present the important results from the EU MILLENNIUM and ADVICE projects, which deal with documentary and early instrumental data from the region under consideration. In addition, authors should place more emphasis on other publications dealing with single years or longer drought periods within the study period that are not cited and discussed, e.g. Pauling et al. 2006, Trigo et al. 2009; Smerdon et al. 2017 et al. and the references therein. It is important to clearly state what has been done so far, how the new data is new and/or different and explain how this study goes beyond the current state of research and where the information is complementary and confirms recent findings. The authors have mentioned important publications by Domínguez-Castro and Tejedor, but they need to be addressed and compared in more detail.
It is not entirely clear how the authors compare document-based drought information (which is descriptive and feeds into an index which is subjective) and the index-based information in the instrumental period, which is based on observations. The two sections on documentary information and instrumental data need to be better linked and compared. Currently, the two parts are separate and need to be better linked. The discussion section could be merged with the results to improve readability and generally shorten the text. How is it possible to compare the index from the past with the differently derived index from meteorological observations? In both cases there are uncertainties that should be mentioned and discussed, and caution is also needed when interpreting results from different time periods.
Information on the climatology of the Mediterranean: The Mediterranean region does indeed receive considerable precipitation amounts in winter. This is not correctly mentioned in the manuscript and a generally better description of the current spatio-temporal precipitation distribution for the area is required.
The sections labelled "state of the art" do not convey the actual state of the art to the reader, but are too short, sometimes confusing because they do not cite the correct sources and/or do not include the primary sources, and the explanations are too simplified.
Information on recent findings and current understanding of climatic conditions, the role of forcing factors (solar, land use, volcanoes, CO2, etc.) and regional impacts of tropical volcanoes during the period under study also need to be more carefully updated and analysed. At the regional and subcontinental level, there are also many new findings that are important for understanding past drought events in north-eastern Spain. For example, the statistical and dynamical explanations for the seasonal and regional climate impacts (temperature, precipitation, circulation) following strong tropical volcanic eruptions are discussed in Fischer et al. 2007 and others. Fischer et al. was cited, but the content and reference to this study need to be emphasised more strongly. For Tambora in particular, the following references should be cited and used for comparison: Raible et al. 2015; Luterbacher and Pfister, 2015; Luterbacher et al. 2016 and Trigo et al. 2009 for the case of Tambora and regional drought in Iberia.
In addition, the physical relationships associated with the occurrence of drought in the past and their comparison with the current situation are presented. The article suggests that the changes in solar radiation during the Dalton Minimum are relevant, but no evidence is provided for a possible link between the solar radiation and drought. Personally, I do not believe that there is a physical mechanism linking the changes in solar radiation during the dry season to hydroclimatic phenomena at the local scale during certain seasons. The authors could make a more convincing case if they find natural variations in their data, or if the extent and intensity of local to regional drought patterns in certain years/periods is related to strong tropical eruptions, and if so, justify this.
Generally, the results section is very long and can be shortened by at least 25%.
References mentioned above:
Luterbacher, J., and Pfister, C., 2015: The year without a summer. Nature Geosci., 8, 246-248.
Pauling, A., Luterbacher, J., Casty, C., and Wanner, H., 2006: 500 years of gridded high-resolution precipitation reconstructions over Europe and the connection to large-scale circulation. Clim. Dynam. 26, 387-405.
Raible, C.C., Brönnimann, S., Auchmann, R., Brohan, P., Frölicher, T., Graf, H.F., Jones, P., Luterbacher, J., Muthers, S., Robock, A., Self, S., Sudrajat, A., Timmreck, C., and Wegmann, M., 2016: Tambora 1815 as a test case for high impact volcanic eruptions: Earth system effects. Wires Clim Change, 7, 569-589.
Smerdon, J.E., et al. 2017: Comparing data and model estimates of hydroclimate variability and change over the Common Era. Clim Past. 13, 1851–1900.
Trigo, R.M., Vaquero, J.M., Alcoforado, M.J., Barriendos, M., Taborda, J., Garcia-Herrera, R., and Luterbacher, J., 2009: Iberia in 1816, the year without summer. Int. J. Climatol., 29, 99–115.
Citation: https://doi.org/10.5194/egusphere-2023-2177-RC1 -
AC2: 'Reply on RC1', Josep Barriendos, 02 Mar 2024
Answer:
The authors express their gratitude for the suggestions made in this review by Referee #1. In the following text, we provide a detailed answer to all those comments that have been suggested by Referee #1.
Comment:
The authors present new high-resolution hydrometeorological and climatological data for north-eastern Spain for the period of the late 18th and early 19th centuries. This is important because the authors, who are very experienced in the field of regional historical climatology, provide new insights from reliable and highly relevant documentary evidence, so-called rogations, and place them in the context of today's drought conditions. The topic is therefore suitable for the journal and the reviewer is very much in favour of publishing the article after revision. However, some sections need to be reconsidered and rewritten. Currently, the paper is rather descriptive and speculative and needs more scientific basis and arguments for the conclusions the authors draw.
In addition, the manuscript needs extensive English editing.
Answer:
Thank you for this suggestion. Along with the rewritten paragraphs of the introduction and results, the other sections (methodology and discussion) have been edited to improve the language used.
Comment:
Below are some general comments that should be taken into account. They are not in any particular order and should be addressed in addition to the general statements above:
Abstract/conclusions:
These sections are rather general and duplicate text from other sections. Both sections need to be refocused when revising the paper.
Answer:
We understand that it is not convenient to reiterate content in an academic text. In this regard, we have rewritten the abstract and conclusions to make them more normative and to show only the most significant aspects of the work. Nevertheless, these sections still contain information similar to other sections, in order to give a complete synthesis view of the work.
Comment:
Introduction:
This section should include the drought definitions from the IPCC's latest AR6.
Answer:
Thank you for this suggestion. We consider it very convenient.
We agree to add the IPCC definition to the definitions already made to the concept of drought. The definition in the IPCC Glossary AR6 of 2022 has been used. The definitions that appear in this glossary for the different types of droughts have also been added.
Comment:
Further, this section and the objectives do not yet provide the reader with the necessary justification as to why this paper is necessary, what has been published on this topic so far and what new elements the authors intend to cover in this publication. These sections therefore need to be better structured and reflect the state of research in this area.
Answer:
We appreciate the suggestion to strengthen the justification of the article. The introduction section with the justification has been extensively modified to add more references and make the section clearer.
Comment:
The section on the current state of historical drought research is not complete. The authors also need to present the important results from the EU MILLENNIUM and ADVICE projects, which deal with documentary and early instrumental data from the region under consideration.
Answer:
References derived from these projects have been accessed and their results have been considered in the text. Especially from the MILLENIUM project which offers more recent results.
Comment:
In addition, authors should place more emphasis on other publications dealing with single years or longer drought periods within the study period that are not cited and discussed, e.g. Pauling et al. 2006, Trigo et al. 2009; Smerdon et al. 2017 et al. and the references therein. It is important to clearly state what has been done so far, how the new data is new and/or different and explain how this study goes beyond the current state of research and where the information is complementary and confirms recent findings. The authors have mentioned important publications by Domínguez-Castro and Tejedor, but they need to be addressed and compared in more detail.
Answer:
We have consulted and incorporated more references to justify the interest of the work and to place it in the context of rainfall variability at different time scales and with the use of different sources of information.
Comment:
It is not entirely clear how the authors compare document-based drought information (which is descriptive and feeds into an index which is subjective) and the index-based information in the instrumental period, which is based on observations. The two sections on documentary information and instrumental data need to be better linked and compared. Currently, the two parts are separate and need to be better linked. The discussion section could be merged with the results to improve readability and generally shorten the text. How is it possible to compare the index from the past with the differently derived index from meteorological observations? In both cases there are uncertainties that should be mentioned and discussed, and caution is also needed when interpreting results from different time periods.
Answer:
We started with two very different blocks of information (historical documentary proxy and instrumental records). The origin and treatment applied to each has been explained. Up to this point, the treatment has been separated. However, the results obtained in the pluviometric variability of the historical proxy and the instrumental record have been analysed jointly for the reconstruction and characterisation of the anomaly under study (See figure 8 of the revised manuscript, in the discussion of the results). Statistical correlations have also been obtained between both sets of information. The results and conclusions of the work are based on the simultaneous behaviour of both types of information.
We do not consider that the results and the discussion have to be put together as they perform different functions.
Comment:
Information on the climatology of the Mediterranean: The Mediterranean region does indeed receive considerable precipitation amounts in winter. This is not correctly mentioned in the manuscript and a generally better description of the current spatio-temporal precipitation distribution for the area is required.
Answer:
In the introduction, winter in the Mediterranean climate is presented as a season of low precipitation. In the text, the regional varieties of the Mediterranean climate of the Spanish Mediterranean coast have been clarified in relation to the seasonal distribution of precipitation. Basically, two varieties are distinguished according to the prominence of spring or winter as a secondary peak of annual precipitation. All of this is based on the premise of the main amount of rainfall in the autumn months (mainly October and November) and the virtual absence of rainfall in summer, a defining feature of climates with a subtropical link (subtropical cell of the Azores), such as the Mediterranean climate type. This part of the text has been modified to be clearer and to mention that rainfall is low on average compared to the other rainy seasons (autumn and spring).
Comment:
The sections labelled "state of the art" do not convey the actual state of the art to the reader, but are too short, sometimes confusing because they do not cite the correct sources and/or do not include the primary sources, and the explanations are too simplified.
Answer:
This section has been reinforced and completed in order to be more specific and to add recent references to authors who have studied droughts in Spain using historical data. Its name has also been modified to focus it on the subject under study.
Comment:
Information on recent findings and current understanding of climatic conditions, the role of forcing factors (solar, land use, volcanoes, CO2, etc.) and regional impacts of tropical volcanoes during the period under study also need to be more carefully updated and analysed. At the regional and subcontinental level, there are also many new findings that are important for understanding past drought events in north-eastern Spain. For example, the statistical and dynamical explanations for the seasonal and regional climate impacts (temperature, precipitation, circulation) following strong tropical volcanic eruptions are discussed in Fischer et al. 2007 and others. Fischer et al. was cited, but the content and reference to this study need to be emphasised more strongly. For Tambora in particular, the following references should be cited and used for comparison: Raible et al. 2015; Luterbacher and Pfister, 2015; Luterbacher et al. 2016 and Trigo et al. 2009 for the case of Tambora and regional drought in Iberia.
Answer:
Thank you for this suggestion. These references to the effects of the Tambora eruption have been added.
Comment:
In addition, the physical relationships associated with the occurrence of drought in the past and their comparison with the current situation are presented. The article suggests that the changes in solar radiation during the Dalton Minimum are relevant, but no evidence is provided for a possible link between the solar radiation and drought. Personally, I do not believe that there is a physical mechanism linking the changes in solar radiation during the dry season to hydroclimatic phenomena at the local scale during certain seasons. The authors could make a more convincing case if they find natural variations in their data, or if the extent and intensity of local to regional drought patterns in certain years/periods is related to strong tropical eruptions, and if so, justify this.
Answer:
We have already specified in the text that there is only a chronological coincidence between the solar minimum and the drought episodes studied in the work. We have stressed that there is no cause-effect relationship between the two phenomena.
Comment:
Generally, the results section is very long and can be shortened by at least 25%.
Answer:
We appreciate the advice to shorten the results section. The text has been edited and some of the figures have been modified and deleted in order to reduce the length of this section.
Comment:
References mentioned above:
Luterbacher, J., and Pfister, C., 2015: The year without a summer. Nature Geosci., 8, 246-248.
Pauling, A., Luterbacher, J., Casty, C., and Wanner, H., 2006: 500 years of gridded high-resolution precipitation reconstructions over Europe and the connection to large-scale circulation. Clim. Dynam. 26, 387-405.
Raible, C.C., Brönnimann, S., Auchmann, R., Brohan, P., Frölicher, T., Graf, H.F., Jones, P., Luterbacher, J., Muthers, S., Robock, A., Self, S., Sudrajat, A., Timmreck, C., and Wegmann, M., 2016: Tambora 1815 as a test case for high impact volcanic eruptions: Earth system effects. Wires Clim Change, 7, 569-589.
Smerdon, J.E., et al. 2017: Comparing data and model estimates of hydroclimate variability and change over the Common Era. Clim Past. 13, 1851–1900.
Trigo, R.M., Vaquero, J.M., Alcoforado, M.J., Barriendos, M., Taborda, J., Garcia-Herrera, R., and Luterbacher, J., 2009: Iberia in 1816, the year without summer. Int. J. Climatol., 29, 99–115.Citation: https://doi.org/10.5194/egusphere-2023-2177-AC2
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AC2: 'Reply on RC1', Josep Barriendos, 02 Mar 2024
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RC2: 'Comment on egusphere-2023-2177', Anonymous Referee #2, 15 Jan 2024
The manuscript titled 'High-resolution reconstruction of drought episodes during the Dalton Solar Minimum (1790–1830) in the Spanish Mediterranean Basin' by Josep Barriendos et al presents an interesting study on droughts in the Spanish Mediterranean coast in the early decades of the 19th century. Despite the study appearing interesting and useful for the climatological community, it has significant issues that clearly prevent its publication in its current form. I will describe below the most important problems and some specific issues.
1. Main problems
1.1. The solar connection
The unifying and guiding element of this study is the Dalton Minimum. This is emphasized in both the title, the abstract, and the main text. However, this element is entirely overlooked in the development of the analysis and discussion presented in this manuscript. This is a serious issue in presentation or explanation, given that the relationships between solar activity and Earth's climate have been a subject of contentious debates in both scientific and socio-political spheres. I am confident that authors, editors, and referees do not wish for this manuscript to be featured in the press with the headline 'a scientific study proves that the Sun causes droughts in Spain.' Yet, that is the impression it currently gives. Therefore, the manuscript needs substantial rewriting to address this issue.
Firstly, the authors need to explain what the Dalton Minimum is. In the last sentence of the manuscript, the authors state: 'In the light of the good results obtained from the combination of these two sources of climatic information, a future line of research for the Dalton Solar Minimum and other relevant climatic periods would consist of combining the historical data with data from other climatic proxies (especially dendrochronology) and instrumental pressure series, which would allow the understanding of the atmospheric processes on a synoptic scale that directly explain the most severe episodes of drought.' This is entirely incorrect from a conceptual standpoint since the Dalton Minimum is a significant solar episode (not climatic), just as the Little Ice Age (LIA) is not a solar phenomenon but a climatic one.
Indeed, the Dalton Minimum corresponds to solar cycles 5 and 6, although some authors also include solar cycle 7. Two recent studies on the topic indicate the period 1797-1827 (Hayakawa et al., 2020a, 2020b). It is crucial to note that studies in solar physics associate the Dalton Minimum with a Gleissberg cycle minimum (Usoskin et al., 2007; Feynman & Ruzmaikin, 2011) and not with a 'Grand Minimum' of solar activity like the Maunder Minimum (1645-1715) (Usoskin et al., 2015). It is of critical importance because solar physicists and geophysicists do not consider the Dalton Minimum as a 'Grand Minimum' of solar activity. An update on solar activity over the last four centuries can be found in Clette et al. (2023).
The manuscript barely mentions another major climatic forcing factor, which is volcanic forcing. However, at least 60 volcanic eruptions occurred between 1791 and 1830 with a Volcanic Explosivity Index (VEI) ≥3, including 17 with VEI ≥ 4 (Global Volcanism Program, 2013). This should have produced clear climatic signals (Schmidt et al., 2018; Fang et al., 2023).
1.2. Spatial representativeness of the data
The authors use the AMARNA database. In particular, water deficits are obtained from the records of "pro pluvia" rogation ceremonies. Table 2 lists the classification system of the AMARNA database and Figure 6 show in a Table the number of positive ERE cases (FF, PF, PR, SS) and negative ERE cases (DR) for the Spanish river basins in the period 1790-1830 (named by authors "Dalton Solar Minimum").
In this unnumbered table that appears in Figure 6, a brutal difference between the Mediterranean and Atlantic basins can be seen. For example, while in the CIC basin there are a total of 741 cases (223 positive cases and 518 negative cases), there are six basins with a total number of cases less than 10. This brutal asymmetry in the number of cases prevents any spatial analysis of the data as a whole (as is the case in a large part of the manuscript).
To try to explain this critical problem a little more, we can focus our attention on Figure 8, which shows the spatial distribution of "Towns with more than 50 cases of drought". Evidently, Mediterranean cities appear (where there are many cases) and the city of Seville (with 161 total cases in the database for the period studied). And obviously, the cities of the Atlantic zone do not appear because, in general, there are not even 50 total cases in the database for the entire period and the entire basin. The conclusion is that this type of analysis does not contribute anything new. Unfortunately, this manuscript is plenty of this kind of problem.
1.3. Local analysis, global conclusion
The authors also use the Barcelona precipitation series for their analysis. But this implies that the results obtained are local and, often, in the manuscript these results are shown as global for the Mediterranean basin. This creates enormous uncertainties in any reader who knows the differences in the modern precipitation regimes of Barcelona, Murcia, or Malaga, for example.
This could be addressed by analyzing more early instrumental series. Unfortunately, I think that there are no such early precipitation series in the Spanish Mediterranean. However, some long series (even if it does not cover the first half of the 19th century) could be used to check the results obtained for the last 150 years.
On the other hand, there is an enormous amount of literature on droughts on the Spanish Mediterranean coast in recent decades and it seems that the authors of this manuscript have not been able to take advantage of this enormous amount of knowledge to make the analysis of the series of historical precipitation of Barcelona.
A final comment on the precipitation series used is obligatory. The authors have concatenated several precipitation series from different stations in Barcelona for the most modern period. This needs a clear justification for the reader who expects there to be a reference series in the city from the Spanish or Catalan meteorological agency without requiring so many station changes (which raise suspicions about the quality of the data).
2. Other problems
a. Section 1.2. State of the Art of Historical Droughts Studies
This section reviews the development of “Historical Droughts Studies” but surprisingly does not include the most recent works on the subject. Obviously, I do not intend for all recent work to be included. But I consider that there are very significant recent works that should be included here. A notable example is the creation of an international database of rogation dates (Domínguez-Castro et al, 2021), which provides the international scientific community with more than 3,500 rogation celebration dates for 11 countries in recent centuries. Likewise, it could be interesting to put in this context some recent works on rogations both outside (Garza-Merodio, 2017; Garnier, 2019) and within Iberia (Fragoso et al, 2018; Bravo-Paredes, 2020).
b. Quality of Figures
A large number of figures present important deficiencies such as not having “labels” for the horizontal or vertical axes, which makes the reader's interpretation extremely difficult. There are also figures that include tables… This is not very standard in scientific publications.
c. Writting problems
My native language is not English, but it seems clear that the writing of this manuscript needs to improve a lot. Some expressions are Spanish phrases literally translated into English that are probably not understood by many readers. Furthermore, the order of words in sentences sometimes significantly affects their meaning, such as “Only three drought episodes are notable outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24)” which should be “Only three noteworthy drought episodes are outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24). There are also single unconnected words in some places. For example, in the caption of figure 6 it reads: “[…] river basins. Dalton Solar Minimum (1790-1830). A list […]”
d. Unrecognized work
I consider that the authors of this manuscript do not recognize and do not give sufficient credit to research groups that work on droughts (historical and modern) in Iberia. A notable example is that Ricardo Trigo's pioneering work on the year without a summer is not cited (Trigo et al, 2009). Any serious work that aims to study the climate of a region of Iberia in the first decades of the 19th century must compare its results with this pioneering work and must show how his work relates to this study. Something similar occurs with the great achievements obtained by Sergio Vicente-Serrano and his group in the area of droughts, including their characterization with different indices. I do not understand that any results shown in this manuscript have a connection with the relevant works published by this research group. If the authors managed to connect their analysis and results with this type of work, they would gain strength and support for their ideas.
3. Conclusion
In short, although I think that the severe droughts of the first decades of the 19th century detected by the authors should be studied, the problems that I detect in this manuscript clearly prevent its publication.
I think the general approach is wrong and dangerous. You cannot frame this study in the Dalton Minimum and then completely ignore solar forcing. This approach must be more rigorous and detailed. On the other hand, I detect important problems both in the data from documents (lack of spatial homogeneity) and in the instrumental data (lack of global representativeness). This clearly affects both the analyzes carried out and the results, as I have briefly shown above.
Finally, the problems are so deep that I recommend rejecting this article for publication, despite the interest of this topic of study.
References
Bravo-Paredes, N., et al (2020) Pro-pluvia rogation ceremonies in Extremadura (Spain): Are they a good proxy of winter NAO? Atmosphere (Basel), 11(3), 282.
Clette et al. (2023) “Recalibration of the Sunspot Number: Status Report” Solar Physics 298, 44.
Hayakawa, Hisashi et al. (2020a) "Thaddäus Derfflinger's Sunspot Observations during 1802–1824: A Primary Reference to Understand the Dalton Minimum", in The Astrophysical Journal, 890, 98.
Hayakawa, Hisashi et al. (2020b) "The Solar Corona during the Total Eclipse on 1806 June 16: Graphical Evidence of the Coronal Structure during the Dalton Minimum", The Astrophysical Journal, 900, 114.
Fang, S.-W., Sigl, M., Toohey, M., Jungclaus, J., Zanchettin, D., & Timmreck, C. (2023). The role of small to moderate volcanic eruptions in the early 19th century climate. Geophysical Research Letters, 50, e2023GL105307.
Feynman, J., Ruzmaikin, A. (2011) “The Sun's Strange Behavior: Maunder Minimum or Gleissberg Cycle?” Solar Physics, Volume 272, Issue 2, article id.351
Fragoso, M., Carraça, M. D. G. & Alcoforado, M. J. (2018) Droughts in Portugal in the 18th century: A study based on newly found documentary data. Int. J. Climatol. 38, 5522.
Garnier, E. (2019) Historic Drought from archives: Beyond the Instrumental Record. in Drought Science and Policy (ed. Iglesias A., Assimacopoulos D. & Van Lanen, H. A. J.) 45–67 (Wiley-Blackwell).
Garza-Merodio, G. G. (2017) Variabilidad climática en México a través de fuentes documentales (siglos XVI al XIX). (Instituto de Geografía, Universidad Nacional Autónoma de México).
Global Volcanism Program (2013). Global volcanism program. Volcanoes of the World. https://doi.org/10.5479/si.GVP.VOTW4-2013
Schmidt, A., Mills, M. J., Ghan, S., Gregory, J. M., Allan, R. P., Andrews, T., et al. (2018). Volcanic radiative forcing from 1979 to 2015. Journal of Geophysical Research: Atmospheres, 123(22), 12491–12508.
Trigo et al. (2009) “Iberia in 1816, the year without a summer” International Journal of Climatology 29, 99.
Usoskin, I. G.; Solanki, S. K.; Kovaltsov, G. A. (2007) Grand minima and maxima of solar activity: new observational constraints, Astronomy and Astrophysics, Volume 471, Issue 1, pp.301-309.
Usoskin et al. (2015) “The Maunder minimum (1645–1715) was indeed a Grand minimum: A reassessment of multiple datasets” Astronomy & Astrophysics 581, A95.
Citation: https://doi.org/10.5194/egusphere-2023-2177-RC2 -
AC3: 'Reply on RC2', Josep Barriendos, 02 Mar 2024
Answer:
The authors express their gratitude for the suggestions made in this review by Referee #2. In the following text, we provide a detailed answer to all those comments that have been suggested by Referee #2.
Comment:
The manuscript titled 'High-resolution reconstruction of drought episodes during the Dalton Solar Minimum (1790–1830) in the Spanish Mediterranean Basin' by Josep Barriendos et al presents an interesting study on droughts in the Spanish Mediterranean coast in the early decades of the 19th century. Despite the study appearing interesting and useful for the climatological community, it has significant issues that clearly prevent its publication in its current form. I will describe below the most important problems and some specific issues.
1. Main problems
1.1. The solar connection
The unifying and guiding element of this study is the Dalton Minimum. This is emphasized in both the title, the abstract, and the main text. However, this element is entirely overlooked in the development of the analysis and discussion presented in this manuscript. This is a serious issue in presentation or explanation, given that the relationships between solar activity and Earth's climate have been a subject of contentious debates in both scientific and socio-political spheres. I am confident that authors, editors, and referees do not wish for this manuscript to be featured in the press with the headline 'a scientific study proves that the Sun causes droughts in Spain.' Yet, that is the impression it currently gives. Therefore, the manuscript needs substantial rewriting to address this issue.
Answer:
The intention of the authors was not to relate any solar phenomenon to terrestrial climate variability, as this is a research field that is still open and has many research questions to be solved. Indeed, accepting the reviewer's point of view, we want to adjust the definition of our work by radically changing the title of the study and the meaning of the expressions between the Dalton Solar Minimum and the climate variability we describe. We have proposed a general temporal definition ("Early 19th Century"). Our study does NOT intend to analyse the Solar Dalton Minimum or any other interrelationship with phenomena in the Earth's atmosphere that are still under investigation. Only in subsequent research, when we have a temporal sequence with more similar drought episodes, will we be in a position to work with specialists to provide insights into episodes or anomalies that may be associated with these drought events.
Comment:
Firstly, the authors need to explain what the Dalton Minimum is. In the last sentence of the manuscript, the authors state: 'In the light of the good results obtained from the combination of these two sources of climatic information, a future line of research for the Dalton Solar Minimum and other relevant climatic periods would consist of combining the historical data with data from other climatic proxies (especially dendrochronology) and instrumental pressure series, which would allow the understanding of the atmospheric processes on a synoptic scale that directly explain the most severe episodes of drought.' This is entirely incorrect from a conceptual standpoint since the Dalton Minimum is a significant solar episode (not climatic), just as the Little Ice Age (LIA) is not a solar phenomenon but a climatic one.
Answer:
We fully agree with your comment on the treatment of the Dalton Solar Minimum and the climate anomaly under study. We have, according to your criterion and that of the other reviewers, correctly redefined this erroneous interrelation. We regret having expressed this misconception and have corrected it both in the contents of the manuscript and in the title itself. Precisely in line with this review, it can be understood that we do not deal in detail with the characteristics of the Dalton Solar Minimum, since this is not our thematic area of expertise.
Our intention in using the concept of the Dalton Solar Minimum was only to provide the reader with a temporal location of our work using as a reference another natural phenomenon that occurs in a similar chronology. Our approach had no unscientific intention, but rather used a pattern already employed by the scientific community in historical climatology in which a solar minimum is compared with climatic anomalies: Frenzel, B. (editor), 1994. Within this work there are several articles whose titles express the study of climatic anomalies "during the late Maunder Minimum (1675-1715)".
Comment:
Indeed, the Dalton Minimum corresponds to solar cycles 5 and 6, although some authors also include solar cycle 7. Two recent studies on the topic indicate the period 1797-1827 (Hayakawa et al., 2020a, 2020b). It is crucial to note that studies in solar physics associate the Dalton Minimum with a Gleissberg cycle minimum (Usoskin et al., 2007; Feynman & Ruzmaikin, 2011) and not with a 'Grand Minimum' of solar activity like the Maunder Minimum (1645-1715) (Usoskin et al., 2015). It is of critical importance because solar physicists and geophysicists do not consider the Dalton Minimum as a 'Grand Minimum' of solar activity. An update on solar activity over the last four centuries can be found in Clette et al. (2023).
Answer:
We are grateful for these explanations, but the criticism regarding the use of the Dalton Solar Minimum concept is accepted and we do not intend in this work to discuss any aspect that relates the climatic variability of pluviometric extremes with the behaviour of solar radiation. We omit the introduction of details on the behaviour of solar radiation because they are beyond the scope of this paper.
Comment:
The manuscript barely mentions another major climatic forcing factor, which is volcanic forcing. However, at least 60 volcanic eruptions occurred between 1791 and 1830 with a Volcanic Explosivity Index (VEI) ≥3, including 17 with VEI ≥ 4 (Global Volcanism Program, 2013). This should have produced clear climatic signals (Schmidt et al., 2018; Fang et al., 2023).
Answer:
In this aspect of volcanic activity, we have followed the criteria for the most significant explosive volcanic eruptions and their possible relationship with climatic anomalies that appear in a doctoral thesis working within the geographical field of this study (Prohom, 2003).
In any case, we are grateful for the detailed information provided and we include it in the text because it improves the quality of the text (See lines 240 to 243 of the revised manuscript).
Comment:
1.2. Spatial representativeness of the data
The authors use the AMARNA database. In particular, water deficits are obtained from the records of "pro pluvia" rogation ceremonies. Table 2 lists the classification system of the AMARNA database and Figure 6 show in a Table the number of positive ERE cases (FF, PF, PR, SS) and negative ERE cases (DR) for the Spanish river basins in the period 1790-1830 (named by authors "Dalton Solar Minimum").
In this unnumbered table that appears in Figure 6, a brutal difference between the Mediterranean and Atlantic basins can be seen. For example, while in the CIC basin there are a total of 741 cases (223 positive cases and 518 negative cases), there are six basins with a total number of cases less than 10. This brutal asymmetry in the number of cases prevents any spatial analysis of the data as a whole (as is the case in a large part of the manuscript).To try to explain this critical problem a little more, we can focus our attention on Figure 8, which shows the spatial distribution of "Towns with more than 50 cases of drought". Evidently, Mediterranean cities appear (where there are many cases) and the city of Seville (with 161 total cases in the database for the period studied). And obviously, the cities of the Atlantic zone do not appear because, in general, there are not even 50 total cases in the database for the entire period and the entire basin. The conclusion is that this type of analysis does not contribute anything new. Unfortunately, this manuscript is plenty of this kind of problem.
Answer:
We understand the criticism regarding the great difference in the number of episodes and cases between the Mediterranean and Atlantic basins. In our approach, we do not intend to analyse drought in all of Spain. The title already makes it clear that the core of the work focuses on the Mediterranean basin of the Iberian Peninsula. For us, the material available on the Atlantic basin only constitutes a reinforcement or complement to the analysis of the core material from the Mediterranean area.
In response to your comment, we accept that this aspect was not sufficiently explained in the section on sources and methods and we proceed to introduce an explanatory paragraph in the text (See lines 490 to 495 of the revised manuscript).
Comment:
1.3. Local analysis, global conclusion
The authors also use the Barcelona precipitation series for their analysis. But this implies that the results obtained are local and, often, in the manuscript these results are shown as global for the Mediterranean basin. This creates enormous uncertainties in any reader who knows the differences in the modern precipitation regimes of Barcelona, Murcia, or Malaga, for example.
This could be addressed by analyzing more early instrumental series. Unfortunately, I think that there are no such early precipitation series in the Spanish Mediterranean. However, some long series (even if it does not cover the first half of the 19th century) could be used to check the results obtained for the last 150 years.
Answer:
We understand the limitation that exists in the study of this type of hydrometeorological anomalies with respect to the availability of early instrumental series. In our work we have used the material available for the period under study and, to date, we do not know of any other instrumental series for the period 1790-1830. We only have some short time series for the city of Valencia that we are in the process of digitising, but without the precipitation variable. On the Atlantic side, Madrid covers this period, but without precipitation records. At least, in the archival work we have done, this variable does not appear. Finally, the observations of the Spanish Navy in Cadiz and the Royal Navy in Gibraltar provide precipitation records, but at low resolution or with important gaps. We accept that the use of a single instrumental series can be considered a localism, but we have worked with the best possible material and in any case the comparison of instrumental and historical records has seemed to us to be a correct procedure for the characterisation of drought episodes.
Nevertheless, given the limited instrumental series available, we have qualified the references to the Barcelona series and its possible value as a series to show regional anomalies. In addition, we have added a paragraph on this possible bias in the available data (See lines 404 to 407 of the revised manuscript). Finally, it should be noted that the study refers to the Spanish Mediterranean basins, but with a special focus on the basins of Catalonia. In this sense, the Barcelona instrumental series does show spatio-temporally coherent variability patterns at the level of these basins.
Comment:
On the other hand, there is an enormous amount of literature on droughts on the Spanish Mediterranean coast in recent decades and it seems that the authors of this manuscript have not been able to take advantage of this enormous amount of knowledge to make the analysis of the series of historical precipitation of Barcelona.
Answer:
The present work uses the historical materials with which previous studies on climate variability in historical climatology have been developed for Barcelona and Catalonia as a whole. In this regard, we have consulted references such as Dominguez-Castro et al., 2012, and others which have been added in section 1.2 Historical Droughts Studies in Spain.
Until now, the works developed used numerical indices at low temporal resolution, whereas in the present work we have taken a new approach to analysis using the historical material at daily and monthly resolutions.
Comment:
A final comment on the precipitation series used is obligatory. The authors have concatenated several precipitation series from different stations in Barcelona for the most modern period. This needs a clear justification for the reader who expects there to be a reference series in the city from the Spanish or Catalan meteorological agency without requiring so many station changes (which raise suspicions about the quality of the data).
Answer:
We fully accept this criticism regarding the description of the different sections of the Barcelona precipitation series. We understand that over the last 240 years this series have had very different locations and observation conditions. To show the reader these details, we introduce some explanatory paragraphs in section 2.1. detailing the basic characteristics of both the sections used in the Prohom et al., 2016 paper and in the 2014-2022 update section (See lines 409 to 421 of the revised manuscript).
Comment:
2. Other problems
a. Section 1.2. State of the Art of Historical Droughts Studies
This section reviews the development of “Historical Droughts Studies” but surprisingly does not include the most recent works on the subject. Obviously, I do not intend for all recent work to be included. But I consider that there are very significant recent works that should be included here. A notable example is the creation of an international database of rogation dates (Domínguez-Castro et al, 2021), which provides the international scientific community with more than 3,500 rogation celebration dates for 11 countries in recent centuries. Likewise, it could be interesting to put in this context some recent works on rogations both outside (Garza-Merodio, 2017; Garnier, 2019) and within Iberia (Fragoso et al, 2018; Bravo-Paredes, 2020).
Answer:
We are grateful for the effort made in referencing recent works on historical droughts, which have been included. In addition to these indications, we have also taken good account of the indications of the other reviewers. With all this, we have drafted some additional paragraphs to be introduced in the State of the Art, which we believe considerably improve its content (See lines 294 to 306 of the revised manuscript). Thank you again.
Comment:
b. Quality of Figures
A large number of figures present important deficiencies such as not having “labels” for the horizontal or vertical axes, which makes the reader's interpretation extremely difficult. There are also figures that include tables… This is not very standard in scientific publications.
Answer:
We have addressed this aspect by improving almost all the figures, following the indications of the 3 reviewers at all times. We are grateful for the effort made by the reviewers, especially in this aspect.
Comment:
c. Writting problems
My native language is not English, but it seems clear that the writing of this manuscript needs to improve a lot. Some expressions are Spanish phrases literally translated into English that are probably not understood by many readers. Furthermore, the order of words in sentences sometimes significantly affects their meaning, such as “Only three drought episodes are notable outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24)” which should be “Only three noteworthy drought episodes are outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24). There are also single unconnected words in some places. For example, in the caption of figure 6 it reads: “[…] river basins. Dalton Solar Minimum (1790-1830). A list […]”
Answer:
A detailed review has been carried out and we believe that a substantial improvement has been made in this area.
Comment:
d. Unrecognized work
I consider that the authors of this manuscript do not recognize and do not give sufficient credit to research groups that work on droughts (historical and modern) in Iberia. A notable example is that Ricardo Trigo's pioneering work on the year without a summer is not cited (Trigo et al, 2009). Any serious work that aims to study the climate of a region of Iberia in the first decades of the 19th century must compare its results with this pioneering work and must show how his work relates to this study. Something similar occurs with the great achievements obtained by Sergio Vicente-Serrano and his group in the area of droughts, including their characterization with different indices. I do not understand that any results shown in this manuscript have a connection with the relevant works published by this research group. If the authors managed to connect their analysis and results with this type of work, they would gain strength and support for their ideas.
Answer:
References on Ricardo Trigo have been conveniently included. His work, in which some of the co-authors of this paper participated, focuses on a very specific period and therefore we had not considered its inclusion from the beginning. In the revised version, this reference and others by the same author have been included, following the reviewer's suggestions, in this commentary and in previous comments (See lines 173 to 174 of the revised manuscript).
With respect to the work of Sergio Vicente-Serrano and his research group, we are familiar with their work. In this regard, we have used their methodologies and have referenced them appropriately in the revised version of the paper and in line with the response to previous suggestions. We have also referenced some works of members of that research group that used documentary sources, although they are already known materials elaborated by one of the co-authors of the present work. Our contribution in this work is based on a singularized approach for drought episodes in high temporal resolution that uses much more defined or concrete materials.
Comment:
3. Conclusion
In short, although I think that the severe droughts of the first decades of the 19th century detected by the authors should be studied, the problems that I detect in this manuscript clearly prevent its publication.
I think the general approach is wrong and dangerous. You cannot frame this study in the Dalton Minimum and then completely ignore solar forcing. This approach must be more rigorous and detailed. On the other hand, I detect important problems both in the data from documents (lack of spatial homogeneity) and in the instrumental data (lack of global representativeness). This clearly affects both the analyzes carried out and the results, as I have briefly shown above.
Finally, the problems are so deep that I recommend rejecting this article for publication, despite the interest of this topic of study.
Answer:
We are extremely grateful for the contributions and review efforts of the three reviewers involved. We have accepted and integrated most of the criticisms and suggestions for improvement. We believe that the effort made by both parties has contributed to a substantial improvement in the quality of the manuscript. For this reason, we hope that the result and negative evaluation of the present work can change towards a positive evaluation.
Comment:
ReferencesBravo-Paredes, N., et al (2020) Pro-pluvia rogation ceremonies in Extremadura (Spain): Are they a good proxy of winter NAO? Atmosphere (Basel), 11(3), 282.
Clette et al. (2023) “Recalibration of the Sunspot Number: Status Report” Solar Physics 298, 44.Hayakawa, Hisashi et al. (2020a) "Thaddäus Derfflinger's Sunspot Observations during 1802–1824: A Primary Reference to Understand the Dalton Minimum", in The Astrophysical Journal, 890, 98.
Hayakawa, Hisashi et al. (2020b) "The Solar Corona during the Total Eclipse on 1806 June 16: Graphical Evidence of the Coronal Structure during the Dalton Minimum", The Astrophysical Journal, 900, 114.
Fang, S.-W., Sigl, M., Toohey, M., Jungclaus, J., Zanchettin, D., & Timmreck, C. (2023). The role of small to moderate volcanic eruptions in the early 19th century climate. Geophysical Research Letters, 50, e2023GL105307.
Feynman, J., Ruzmaikin, A. (2011) “The Sun's Strange Behavior: Maunder Minimum or Gleissberg Cycle?” Solar Physics, Volume 272, Issue 2, article id.351
Fragoso, M., Carraça, M. D. G. & Alcoforado, M. J. (2018) Droughts in Portugal in the 18th century: A study based on newly found documentary data. Int. J. Climatol. 38, 5522.
Garnier, E. (2019) Historic Drought from archives: Beyond the Instrumental Record. in Drought Science and Policy (ed. Iglesias A., Assimacopoulos D. & Van Lanen, H. A. J.) 45–67 (Wiley-Blackwell).
Garza-Merodio, G. G. (2017) Variabilidad climática en México a través de fuentes documentales (siglos XVI al XIX). (Instituto de Geografía, Universidad Nacional Autónoma de México).
Global Volcanism Program (2013). Global volcanism program. Volcanoes of the World. https://doi.org/10.5479/si.GVP.VOTW4-2013
Schmidt, A., Mills, M. J., Ghan, S., Gregory, J. M., Allan, R. P., Andrews, T., et al. (2018). Volcanic radiative forcing from 1979 to 2015. Journal of Geophysical Research: Atmospheres, 123(22), 12491–12508.
Trigo et al. (2009) “Iberia in 1816, the year without a summer” International Journal of Climatology 29, 99.
Usoskin, I. G.; Solanki, S. K.; Kovaltsov, G. A. (2007) Grand minima and maxima of solar activity: new observational constraints, Astronomy and Astrophysics, Volume 471, Issue 1, pp.301-309.
Usoskin et al. (2015) “The Maunder minimum (1645–1715) was indeed a Grand minimum: A reassessment of multiple datasets” Astronomy & Astrophysics 581, A95.
Citation: https://doi.org/10.5194/egusphere-2023-2177-AC3
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AC3: 'Reply on RC2', Josep Barriendos, 02 Mar 2024
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RC3: 'Comment on egusphere-2023-2177', Anonymous Referee #3, 23 Jan 2024
The article analyzes droughts in the Mediterranean coast of the Iberian Peninsula during the period 1790-1830, utilizing pro-pluvia rogations and early instrumental data from Barcelona. While experiments combining documentary sources and long instrumental data are inherently interesting, this article, in its current form, lacks focus and is speculative, making it difficult to read. Additionally, the methods used are either unjustified or incorrect, and most of the conclusions are speculative, poorly supported by the results. The editing also lacks attention to detail, with figures lacking labels on axes, duplicate information in tables and figures, references that do not appear in the reference list (e.g., Morron 2020), and large parts of the text that are unnecessary or could be highly summarized for the paper's objectives
I will begin my review by addressing the main problems with the proposed objectives. In the abstract, the principal objective is stated as follows: 'The objective of this study is to analyze the occurrence and magnitude of extreme droughts, lasting more than a year, in Spain during the Dalton Solar Minimum period (1790-1830).' However, this objective differs slightly from the main objective expressed in section 1.3: 'Analyze the patterns of drought episodes that affected the Spanish Mediterranean Basin during the Dalton Solar Minimum between 1790 and 1830 using instrumental and historical sources.' Several issues arise in achieving this objective. Firstly, it is necessary to clearly define the study area based on the data used. In the abstract, the study area is Spain, while in section 1.3, it is the Spanish Mediterranean Basin. Upon reading the paper, it becomes apparent that the correct area of study should be the North Spanish Mediterranean Basin, as most of the information and the most homogenous records are from this area. Secondly, to achieve this objective it is mandatory to clearly define what is considered a drought episode, including its magnitude and duration (both for the instrumental and for the documentary period) . This clarity is lacking in the methodology.
Regarding the 'additional objectives':
- 'To qualitatively and quantitatively extend the AMARNA database on climate risks (Arxius Multidisciplinars per a l’Anàlisi del Risc Natural i Antròpic, from Catalan: Multidisciplinary Archives for the Analysis of Natural and Anthropogenic Risk) to incorporate droughts and different social processes linked to environmental impact in addition to hydrometeorological excesses (Tuset et al., 2022)': This objective stands out as one of the most significant contributions of the paper to the scientific community. It is crucial to provide a detailed description of the qualitative and quantitative improvements made to the AMARNA database. This includes specifics such as the number of new locations and dates of rogation ceremonies incorporated. Additionally, defining the Mediterranean locations covered by the database is essential for understanding the spatial pattern analysis attempted in the paper. The heterogeneity of available data may pose challenges to this analysis, so clarifying the extent and characteristics of the database is vital. It's also important to confirm if the database is publicly available and provide information on how it can be accessed, taking into account the data policy of NHESS (https://www.natural-hazards-and-earth-system-sciences.net/submission.html).
- 'To compile and describe the variability of extreme hydrometeorological events (torrential rainfall and droughts) in the Spanish Mediterranean Basin during the DSM': The utility of analyzing torrential rainfalls alongside the main objective focused on drought events is not clear. If the authors believe it is necessary, they should provide a more detailed explanation of why it adds value to the analysis and how it contributes to the main objective, avoiding introducing unnecessary noise.
- 'To characterize the drought episodes, analyzed from historical data and the instrumental precipitation series of Barcelona, considering their duration, extension, and severity in high resolution for the period analyzed': This objective seems to overlap with the main one. Regardless, it is necessary to clearly define how duration, extension, and severity are computed both from rogation ceremonies and from SPI and SPEI.
- 'To analyze the entire instrumental precipitation series of Barcelona spanning from X to Y in order to characterize periods of drought': I do not understand well the difference among this objective and the previous one. Whats mean 'X to Y??
Now I want to provide some comments order by the appearance in the text no by importance.
L. 43-58: The authors could discuss environmental droughts as a typology of drought, especially when considering their effects on the environment (L. 113).
L. 63-70: The explanation regarding pro pluvia rogations as a proxy for meteorological droughts is not entirely convincing. Previous studies have shown a clear link between rogations and agricultural processes, with seasonality tied to the agricultural calendar. I see the point of the authors about the daily resolution of the proxy, but I think that more evidences are required to affirm that rogation can be considered as a meteorological drought proxy. A comparison of precipitation in Barcelona and rogations at this location could shed light on this, and the authors should address the extrapolation of results to other climates more thoroughly.
L. 85-88: The statement that "the available knowledge focuses on very specific aspects during the instrumental period" is incorrect, and may be considered disrespectful to numerous authors who have worked on various aspects of droughts over the past decades. Citing studies like Van Loon & Van Lanen, 2012, does not support this assertion
L. 184-197: The review of historical droughts in the Iberian Peninsula appears outdated, with the latest papers cited being from 2013. Given the significant advances in the field over the last decade, the authors should update this section with more recent references.
L. 269-271: The use of two different stations to update the series of Barcelona until 2022 is mentioned, but the homogeneity of the final series is not analyzed. Since standardized drought indices are highly sensitive to inhomogeneities, it is crucial to analyze and address potential homogeneity issues in the updated series.
L. 273-319: In this section, the authors need to provide a clearer explanation of how the AMARNA database has been “qualitatively and quantitatively” improved. It is unclear how many new data have been added to the database and how the information processing has been enhanced compared to previous papers. Additionally, instead of Table 3, it may be more beneficial for the authors to present a map showing the locations with information on extremes during the studied period and the length of this records. This really allows the reader to understand the studied area.
L. 327-329: The authors seem unfamiliar with SPEI. Firstly the paper that describe the index is Vicente-Serrano et al. 2010 not Beguería et al. 2010 that describe a global database. The description of SPEI in the text is poor and lacks essential details as that the index try to replicate a balance of water in the atmosphere. The authors should specify how they computed atmospheric evaporative demand. Morover they must define and justify the temporal windows of the index and the threshold to consider drought conditions. These details significantly influence the results and should be thoroughly explained.
L. 377: The term "relative normality" is unclear. The period 1806-1812 is noted as anomalous, due to the scarcity of ERE events, both below the mean. This period coincides with the Peninsular War (1818-1814), raising the possibility of factors affecting the availability of documentary sources or record-keeping during wartime. The authors could provide information on the continuity and homogeneity of the documentary sources analyzed during the studied period to shed light on the observed low density of events.
Figures 2, 3, 4, and 5 contain similar information. Suggest summarizing this information in one or two figures.
L. 386: “This anomaly may be due to the fact that in this basin no specific campaigns for compiling drought information have been carried out” It is necessary to define in all areas if he low number of ERE are due to lack of data. This is manatory to understand figure 6.
Figure 7: Define "case of drought." The abstract mentions droughts lasting more than a year, but this doesn't seem possible here.
Figure 8: Explain how the "potential affected area" is computed.
L. 413: Clarify how the period 1812-1825 is possibly linked to Maldà Oscillation. Explain the nature of this link.
L. 466: Show plots with the severity and duration of droughts.
Figure 14: Methodologically, it doesn't make sense to compute a moving average of SPI or SPEI. I suggest using longer periods for compute the indices as a methodological correct solution.
Figure 15 and Table 6: Contain the same information; consider removing the figure.
Explain why a 12-month SPI and SPEI is used. I suggest considering shorter scales (1-6 months) as damages in Iberia are often related to these scales (Peña-Gallardo et al. 2019 NHESS, 19, 1215–1234).
Include units in the axes of the figures.
Citation: https://doi.org/10.5194/egusphere-2023-2177-RC3 -
AC1: 'Reply on RC3', Josep Barriendos, 02 Mar 2024
Answer:
The authors express their gratitude for the suggestions made in this review by Referee #3. In the following text, we provide a detailed answer to all those comments that have been suggested by Referee #3.
Comment:
The article analyzes droughts in the Mediterranean coast of the Iberian Peninsula during the period 1790-1830, utilizing pro-pluvia rogations and early instrumental data from Barcelona. While experiments combining documentary sources and long instrumental data are inherently interesting, this article, in its current form, lacks focus and is speculative, making it difficult to read. Additionally, the methods used are either unjustified or incorrect, and most of the conclusions are speculative, poorly supported by the results. The editing also lacks attention to detail, with figures lacking labels on axes, duplicate information in tables and figures, references that do not appear in the reference list (e.g., Morron 2020), and large parts of the text that are unnecessary or could be highly summarized for the paper's objectives
Answer:
We appreciate these general comments on the text.
The aspects commented on the text have been corrected. For example, the information is no longer repetitive between tables and figures and the style of the figures has also been edited to be clearer and more homogeneous between the different figures.
The references have been checked to ensure that they were all included in the bibliography and a reference that was misspelled has been rectified in the text, changing Moruno, 2020 for Moruno, 2021.
The remaining valuable comments on the methods used and the conclusions will be answered in detail and with justification in subsequent sections.
Comment:
I will begin my review by addressing the main problems with the proposed objectives. In the abstract, the principal objective is stated as follows: 'The objective of this study is to analyze the occurrence and magnitude of extreme droughts, lasting more than a year, in Spain during the Dalton Solar Minimum period (1790-1830).' However, this objective differs slightly from the main objective expressed in section 1.3: 'Analyze the patterns of drought episodes that affected the Spanish Mediterranean Basin during the Dalton Solar Minimum between 1790 and 1830 using instrumental and historical sources.'
Answer:
We are grateful for this clarification. The more generic reference to "Spain" has been changed from the abstract to "Spanish Mediterranean Basin". Thus, this slight difference has been eliminated by mentioning the same objective in the text (abstract and objectives). The data for the Spanish Atlantic Basin are considered to be used to support the detection and definition of the episodes.
Comment:
Several issues arise in achieving this objective. Firstly, it is necessary to clearly define the study area based on the data used. In the abstract, the study area is Spain, while in section 1.3, it is the Spanish Mediterranean Basin. Upon reading the paper, it becomes apparent that the correct area of study should be the North Spanish Mediterranean Basin, as most of the information and the most homogenous records are from this area.
Answer:
The reference to Spain in the abstract has been modified and the study area is now more coherent, using the expression "Spanish Mediterranean Basin" in all cases.
Regarding the change of the name of the study area to "North Spanish Mediterranean Basin", we appreciate the name suggestion. However, it has been considered among the authors that the original name better encompasses all the information analysed in the article, as it is not only the North Spanish Mediterranean Basin that is being studied. There is a significant amount of information within the "Spanish Mediterranean Basin" that corresponds to the central and southern sections. If the title were changed, as the reviewer suggests, it would not be understood why information from other Spanish territories is included and it would make it difficult to understand droughts as a social and historically interconnected phenomenon between different regions.
Comment:
Secondly, to achieve this objective it is mandatory to clearly define what is considered a drought episode, including its magnitude and duration (both for the instrumental and for the documentary period). This clarity is lacking in the methodology.
Answer:
We are grateful for this comment. We have added a detailed explanation of how we define drought episodes based on the documentary records of public administrative corporations that activate liturgical procedures such as pro pluvia rogations (see lines 339 to 347 of the revised manuscript).
Regarding the definition of the episodes from the instrumental data, this can be found next to the table of episodes in the results. A brief description of the criterion used in this paper to define drought episodes from precipitation data has been prepared. This text is found in the methodology section, within the subsection "2.3 Generation of drought indices" (see lines 396 to 401 of the revised manuscript).
Comment:
Regarding the 'additional objectives':
1. 'To qualitatively and quantitatively extend the AMARNA database on climate risks (Arxius Multidisciplinars per a l’Anàlisi del Risc Natural i Antròpic, from Catalan: Multidisciplinary Archives for the Analysis of Natural and Anthropogenic Risk) to incorporate droughts and different social processes linked to environmental impact in addition to hydrometeorological excesses (Tuset et al., 2022)': This objective stands out as one of the most significant contributions of the paper to the scientific community. It is crucial to provide a detailed description of the qualitative and quantitative improvements made to the AMARNA database. This includes specifics such as the number of new locations and dates of rogation ceremonies incorporated. Additionally, defining the Mediterranean locations covered by the database is essential for understanding the spatial pattern analysis attempted in the paper. The heterogeneity of available data may pose challenges to this analysis, so clarifying the extent and characteristics of the database is vital. It's also important to confirm if the database is publicly available and provide information on how it can be accessed, taking into account the data policy of NHESS (https://www.natural-hazards-and-earth-system-sciences.net/submission.html).
Answer:
The AMARNA database originally only provided data on water excesses recorded in historical periods for the Spanish Mediterranean Basins as a whole. Efforts are currently being made to add data on droughts to the AMARNA database. In this sense, the period from 1790 to 1830 has been a test to see how the recently obtained drought data and the existing water excess data fit together. Thus, the work proposed in this article involved going from 0 cases and episodes of drought for the Early 19th Century to the values with which the study was carried out.
Regarding online access to the AMARNA database: the situation with this project is that it is still under construction and therefore not yet available for public access. Only the period 1790-1830 has been completed, but it is still not publicly accessible because additional records are still being entered. The data used for the study period, however, can be shared upon request to the authors. In line with the NHESS data access policy, this detailed information is now included in the "Data availability" section of the revised manuscript.
In the case of the Early 19th Century, the different efforts to collect and organise the data on water excesses and droughts have resulted in a very characteristic spatial distribution of the data (Figure 1). Most of the points with information on water excesses collected in AMARNA are located in the Spanish Mediterranean basins. On the other hand, the information on droughts reaches points all over Spain, but with a higher density in the territory of Catalonia, between the CHE and the CIC (Figure 1). Some sentences explaining these considerations have been added (lines 489 to 499 of the revised manuscript).
Comment:
2. 'To compile and describe the variability of extreme hydrometeorological events (torrential rainfall and droughts) in the Spanish Mediterranean Basin during the DSM': The utility of analyzing torrential rainfalls alongside the main objective focused on drought events is not clear. If the authors believe it is necessary, they should provide a more detailed explanation of why it adds value to the analysis and how it contributes to the main objective, avoiding introducing unnecessary noise.
Answer:
A sentence has been added to the objectives clarifying the justification for analysing also the behaviour of torrential rainfall (see lines 324 to 326 in the revised manuscript). We understand that the Mediterranean climate has a marked irregularity. And the current situation, together with the modelled future, gives a greater interest in extending the knowledge of extreme situations of the past. Not only independently, but also by analysing these extremes (rainfall deficits and excesses) jointly to see how they interact with each other. In addition, spatio-temporally coherent periods of climatic anomalies have among their main characteristics in the study area, an increase in rainfall irregularity (Gil-Guirado et al., 2016).
The above justification has been included in the revised manuscript (see lines 326 to 328 in the revised manuscript).
This approach will also be applied in other work on the behaviour of extreme hydrometeorological extremes in other periods.
Comment:
3. 'To characterize the drought episodes, analyzed from historical data and the instrumental precipitation series of Barcelona, considering their duration, extension, and severity in high resolution for the period analyzed': This objective seems to overlap with the main one. Regardless, it is necessary to clearly define how duration, extension, and severity are computed both from rogation ceremonies and from SPI and SPEI.
Answer:
We appreciate the feedback. Indeed, additional objective 3 and the main objective are very similar. The main difference is that additional objective 3 takes into consideration the concepts of duration, extent and severity. For this reason, the objective has been rewritten to focus on the use of historical data. The above justification has been included in the revised manuscript (see lines 328 to 330 in the revised manuscript).
Comment:
4. 'To analyze the entire instrumental precipitation series of Barcelona spanning from X to Y in order to characterize periods of drought': I do not understand well the difference among this objective and the previous one. Whats mean 'X to Y??
Answer:
The reference to instrumental data in objective 3 has been deleted. Thus, objective 3 now focuses on historical data while objective 4 focuses on the Barcelona instrumental series. "From X to Y" is an expression used to mean from beginning to end. We have decided to change this expression so that the phrase is not so confusing. The above justification has been included in the revised manuscript (see lines 330 to 332 in the revised manuscript).
Comment:
Now I want to provide some comments order by the appearance in the text no by importance.
L. 43-58: The authors could discuss environmental droughts as a typology of drought, especially when considering their effects on the environment (L. 113).
Answer:
We understand the consideration of this concept of drought and its relevance as outlined by the reviewer. However, we can only consider drought on the basis of the criteria with which the documentary records we use were generated. In other words, we can mostly identify and classify episodes of drought according to their degree of rainfall or meteorological anomaly that affects the development of traditional rainfed crops (long-cycle cereals such as wheat or barley). Unfortunately, the administrative documentary sources in different historical periods in the Hispanic monarchy do not systematically follow the evolution of environmental aspects or the natural environment. For this reason, their introduction in a chronological series would have implied the consideration of inhomogeneous data. Therefore, their analysis has not been included in this article.
Comment:
L. 63-70: The explanation regarding pro pluvia rogations as a proxy for meteorological droughts is not entirely convincing. Previous studies have shown a clear link between rogations and agricultural processes, with seasonality tied to the agricultural calendar. I see the point of the authors about the daily resolution of the proxy, but I think that more evidences are required to affirm that rogation can be considered as a meteorological drought proxy. A comparison of precipitation in Barcelona and rogations at this location could shed light on this, and the authors should address the extrapolation of results to other climates more thoroughly.
Answer:
We appreciate these observations and have addressed this aspect and substantially improved it in the new text. That particular paragraph in the introduction on rogations has been deleted from the text. The information it contained was really confusing and not very explanatory of what the rogations are as a source of information. Moreover, it was a paragraph that did not fit well in that block of the introduction. The explanation of the rogations has now been strengthened in the methodology section in response to the issues raised in your commentary. The above justification has been included in the revised manuscript (see lines 379 to 386 in the revised manuscript). We hope that these changes respond to the reviewer's comment.
Comment:
L. 85-88: The statement that "the available knowledge focuses on very specific aspects during the instrumental period" is incorrect, and may be considered disrespectful to numerous authors who have worked on various aspects of droughts over the past decades. Citing studies like Van Loon & Van Lanen, 2012, does not support this assertion
Answer:
We are grateful for this suggestion. This sentence in its original form was incorrect and did not contribute to the content of the text. The sentence has been deleted to avoid this error.
Comment:
L. 184-197: The review of historical droughts in the Iberian Peninsula appears outdated, with the latest papers cited being from 2013. Given the significant advances in the field over the last decade, the authors should update this section with more recent references.
Answer:
More recent references on the subject have been introduced: Among others, Domínguez-Castro et al., 2021; Cuadrat et al., 2022; Garza-Merodio, 2017; Alberola & Arrioja, 2018; Ramírez-Vega, 2021; However, the authors would like to point out that the subject of historical droughts using documentary sources is still very limited in its development in the study area.
Comment:
L. 269-271: The use of two different stations to update the series of Barcelona until 2022 is mentioned, but the homogeneity of the final series is not analyzed. Since standardized drought indices are highly sensitive to inhomogeneities, it is crucial to analyze and address potential homogeneity issues in the updated series.
Answer:
This study focuses on the detection of severe precipitation anomalies. The homogenisation of the series would be part of an investigation with other objectives based on the same series.
We are aware that the available sections used to complete the Barcelona instrumental series come from points in the city with very different characteristics (from the coast to mountains at 500 m altitude). In our paper we focus on the anomalies within each of these series sections. Rainfall in the Mediterranean climate presents such a marked variability that obtaining a complete homogenised series is an objective and a later stage in this type of research.
In any case, the sections of data used in this study have been validated by the Meteorological Service of Catalonia, as they are official data. The above justification has been included in the revised manuscript (see lines 410 to 416 in the revised manuscript).
Comment:
L. 273-319: In this section, the authors need to provide a clearer explanation of how the AMARNA database has been “qualitatively and quantitatively” improved. It is unclear how many new data have been added to the database and how the information processing has been enhanced compared to previous papers. Additionally, instead of Table 3, it may be more beneficial for the authors to present a map showing the locations with information on extremes during the studied period and the length of this records. This really allows the reader to understand the studied area.
Answer:
An explanatory paragraph has been added on the type of data added to the AMARNA database for this study. Initially, the database only included water excesses and the contribution with the present manuscript is the introduction of information on water deficits. The above justification has been included in the revised manuscript (see lines 476 to 482 in the revised manuscript).
Table 3 has been modified so that it is accompanied by a map showing the various data points available for the study period (1790-1830) (see Figure 1 in the revised manuscript, lines 503-504). This map shows which points provide information on droughts and/or excess water. This allows us to see that, although the density of information for the Mediterranean basin is quite high, the spatial coverage of drought episodes is much more limited.
Comment:
L. 327-329: The authors seem unfamiliar with SPEI. Firstly the paper that describe the index is Vicente-Serrano et al. 2010 not Beguería et al. 2010 that describe a global database. The description of SPEI in the text is poor and lacks essential details as that the index try to replicate a balance of water in the atmosphere. The authors should specify how they computed atmospheric evaporative demand. Morover they must define and justify the temporal windows of the index and the threshold to consider drought conditions. These details significantly influence the results and should be thoroughly explained.
Answer:
We had not realised this serious error. We are very grateful for this observation. The reference has been modified, both in the text and in the bibliography.
A brief description of the index is given in the methodology section (see lines 518 to 523 in the revised manuscript). It is also not the intention of this text to provide an in-depth description of how the indexes work, but only a superficial description. It is not the aim of this publication to carry out a methodological reflection on their use.
We have considered that this type of index is already adequately explained in the scientific literature. For this reason, we have provided the corresponding references and have preferred to provide an overview of each of them, without carrying out a detailed analysis of each one. Instead, and bearing in mind the objectives of this work, we have focused our efforts on analysing the results generated by each of these indices. The contents are related to the objectives of this paper. However, as we pointed out at the beginning of this answer, in relation to SPEI we add the following clarification (see lines 523 to 529 in the revised manuscript): following Vicente-Serrano et al. 2010, in this work we calculate SPEI using monthly temperature and precipitation data. Potential Evapotranspiration (ETP) is calculated using the Thornthwaite (1948) method, which requires only monthly mean temperature. This method uses temperature to calculate a heat index and from this the ETP is determined. The difference between precipitation and ETP represents a simple water balance, and is fitted to a log-logistic distribution to standardise the SPEI over different time scales. This approach allows SPEI to incorporate the effects of temperature variability in the assessment of drought.
Comment:
L. 377: The term "relative normality" is unclear. The period 1806-1812 is noted as anomalous, due to the scarcity of ERE events, both below the mean. This period coincides with the Peninsular War (1818-1814), raising the possibility of factors affecting the availability of documentary sources or record-keeping during wartime. The authors could provide information on the continuity and homogeneity of the documentary sources analyzed during the studied period to shed light on the observed low density of events.
Answer:
The results section has been modified, both in the text and in the figures. In the case of the text where the term "relative normality" appears, it has been deleted and replaced by a clearer text (see lines 564 to 566 in the revised manuscript).
The documentary series consulted have the continuity and homogeneity that is usual in this type of sources. It is understandable that in a war scenario there could be very different types of incidents. However, there are two arguments in favour of homogeneity: firstly, despite the severity of the Napoleonic wars, they were of low intensity for the territory under study. In this case, it was generally a conflict in which the contenders hardly moved and took food resources from the same area. Secondly, the records collected correspond to local authorities, which implies that they are institutions not directly affected by the conflict. Their responsibilities are focused on the basic activities of their immediate territory, such as the development of crops and the collection of water resources for their citizens.
Finally, it can be explained that, in order to compensate for the possible effects on municipal documentation, private documentary sources (diaries and memoirs) appeared during the Napoleonic Wars, which can complement the official documentation.
Comment:
Figures 2, 3, 4, and 5 contain similar information. Suggest summarizing this information in one or two figures.
Answer:
Figures 2, 3, 4 and 5 have been deleted. The information contained in these figures is now shown in a single figure with two diagrams (see figure 2 of the revised manuscript).
Comment:
L. 386: “This anomaly may be due to the fact that in this basin no specific campaigns for compiling drought information have been carried out” It is necessary to define in all areas if he low number of ERE are due to lack of data. This is mandatory to understand figure 6.
Answer:
A paragraph has been introduced explaining this bias, which certainly occurs in the homogeneity of the data (See figure 1 of the revised manuscript). The main cause of this bias is that it has not been possible to work with all the points that we would have liked to due to the workload involved. This work exceeds the objectives of this manuscript, since, although there is an inherent bias in historical documentation, this fact is inherent to the discipline of historical climatology itself. On the other hand, the fact of having data from regions that have been studied in detail, as opposed to others that have been less studied but for which documentation is available, makes it possible to detect the spatial extent of the droughts. This is included among the objectives of the work.
In this sense, the Júcar basin (CHJ), specifically the departments of Valencia and Castellón, have this bias because the same systematic work has not been applied as in other regions for research on historical droughts. This is a research bias that also occurs in the Andalusian Mediterranean basins (CMA), the Guadiana basin (CGN) and the Miño basin in Galicia (NOR). On the other hand, the regions of Murcia (CHS), Alicante (CHS) and Catalonia (CIC and CHE) appear with a good representation of drought due to the campaigns carried out to obtain this information.
Figure 1 of the revised manuscript shows the number of data points that provide information on excess water for these regions.
Comment:
Figure 7: Define "case of drought." The abstract mentions droughts lasting more than a year, but this doesn't seem possible here.
Answer:
A complete description of drought cases has been introduced in the methodology section, in the same sense as detailed below:
Cases are the basic units of documentary record in which there is a mention of some kind of incidence of water deficit. They may be decisions by the authorities to initiate or continue pro-pluvia rogations, they may be qualitative records on rainfall within a drought episode, or records on the decision by the authorities to end the rogations once the drought is considered to be over.
Comment:
Figure 8: Explain how the "potential affected area" is computed.
Answer:
The interpolation and definition of the area potentially affected by drought has been obtained during the process of interpolation of the historical data for each of these episodes. This work has been carried out using Arc Map GIS software, using the Kernel Density tool. The explanation has been added in the footnote of figure 5 (See lines 641 to 646 of the revised manuscript).
The area obtained is logically a geographical abstraction of the territory in which the documented drought situation may be affecting the development of rainfed crops.
Comment:
L. 413: Clarify how the period 1812-1825 is possibly linked to Maldà Oscillation. Explain the nature of this link.
Answer:
The drought we are linking to the Maldà Oscillation is not that of 1812-1825, but an earlier episode from December 1797 to December 1799. The writing has been revised to avoid misunderstandings.
Comment:
L. 466: Show plots with the severity and duration of droughts.
Answer:
The indication pointed out by the reviewer was already available in the manuscript, but at the end of the whole process of analysing the results in that section. However, for the sake of clarity, we have replaced figure 16 attached to table 7 in the old version of the manuscript with a new figure 7 in the new revised version. In this way, and thanks to the reviewer's annotation, the duration and intensity of the different drought episodes analysed are shown more clearly. Likewise, it is now possible to appreciate those episodes whose intensity was higher than the average intensity and duration of all the episodes analysed. In this sense, the exceptional duration and intensity of episodes 6, 7 and 25 stand out.
Comment:
Figure 14: Methodologically, it doesn't make sense to compute a moving average of SPI or SPEI. I suggest using longer periods for compute the indices as a methodological correct solution.
Answer:
Figure 14 has been removed from the text. A panel has been created with the values of the three indices and no moving average is shown for these values (new Figure 6). We have decided to keep moving averages only for values extracted from historical documentation, as this is a procedure commonly used in historical climatology. But moving averages have been removed for drought indices. Indeed, the very computation of drought indices implies a certain effect of temporal aggregation when considering the values of long periods for their calculation.
Comment:
Figure 15 and Table 6: Contain the same information; consider removing the figure.
Answer:
The aim of this figure was to provide a summary and visual image of the discontinuities generated by the indices, following the chronological pattern used in the presentation of the indices themselves (1786-2022). However, the image certainly does not provide information that is not contained in the current table 5, so we have decided to remove it.
Comment:
Explain why a 12-month SPI and SPEI is used. I suggest considering shorter scales (1-6 months) as damages in Iberia are often related to these scales (Peña-Gallardo et al. 2019 NHESS, 19, 1215–1234).
Answer:
We have chosen 12-month indices because we are working with episodes that already have a significant severity. Choosing shorter periods of analysis would lead us to analyse droughts that are practically seasonal and that form a structural part of the climatology of this region, as shown by works such as that of Noguera et al. (2020). This line is followed by other recent scientific works (Mathbout et al., 2021). In addition, this work highlights that the use of various drought indices is especially valid for detecting the most intense drought episodes on a regional scale. We want to focus the study on those episodes of drought that have the most significant social, productive and economic impacts. This is a key point in the work. Some relevant studies, such as Espín-Sánchez and Gil-Guirado (2022), have shown that the socio-environmental systems in the study area presented adaptation and resilience strategies adapted to droughts of high intensity but short duration. However, when the drought lasted for several seasons, social, economic and political problems arose, which are detected in the historical documentation.
Comment:
Include units in the axes of the figures.
Answer:
Thank you for noticing this oversight. In the diagrams where applicable, the units or category names have already been added, as appropriate.
References of the answersEspín-Sánchez, J. A., & Gil-Guirado, S. (2022). Praying for rain, resilience, and social stability in Murcia (southeast Spain). Ecology and Society, 27(2).
Gil-Guirado, S., Espín-Sánchez, J. A., and Prieto, M.: Can we learn from the past? Four hundred years of changes in adaptation to floods and droughts. Measuring the vulnerability in two Hispanic cities, Climatic Change, 139, 183-200, https://doi.org/10.1007/s10584-016-1768-0, 2016
Mathbout, S., Lopez-Bustins, J. A., Royé, D., & Martin-Vide, J. (2021). Mediterranean-scale drought: Regional datasets for exceptional meteorological drought events during 1975–2019. Atmosphere, 12(8), 941.
Noguera, I., Domínguez‐Castro, F., & Vicente‐Serrano, S. M. (2020). Characteristics and trends of flash droughts in Spain, 1961–2018. Annals of the New York Academy of Sciences, 1472(1), 155-172.
Thornthwaite, C. W., 1948: An approach toward a rational classification of climate. Geogr. Rev., 38, 55–94.
Vicente-Serrano, S. M., Beguería, S., and López-Moreno, J. I., A Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation Evapotranspiration Index. Journal of climate, 23(7), 1696-1718. https://doi.org/10.1175/2009JCLI2909.1, 2010.
Citation: https://doi.org/10.5194/egusphere-2023-2177-AC1
Status: closed
-
RC1: 'Comment on egusphere-2023-2177', Anonymous Referee #1, 04 Jan 2024
The authors present new high-resolution hydrometeorological and climatological data for north-eastern Spain for the period of the late 18th and early 19th centuries. This is important because the authors, who are very experienced in the field of regional historical climatology, provide new insights from reliable and highly relevant documentary evidence, so-called rogations, and place them in the context of today's drought conditions. The topic is therefore suitable for the journal and the reviewer is very much in favour of publishing the article after revision. However, some sections need to be reconsidered and rewritten. Currently, the paper is rather descriptive and speculative and needs more scientific basis and arguments for the conclusions the authors draw.
In addition, the manuscript needs extensive English editing.
Below are some general comments that should be taken into account. They are not in any particular order and should be addressed in addition to the general statements above:
Abstract/conclusions: These sections are rather general and duplicate text from other sections. Both sections need to be refocused when revising the paper.
Introduction: This section should include the drought definitions from the IPCC's latest AR6.
Further, this section and the objectives do not yet provide the reader with the necessary justification as to why this paper is necessary, what has been published on this topic so far and what new elements the authors intend to cover in this publication. These sections therefore need to be better structured and reflect the state of research in this area.
The section on the current state of historical drought research is not complete. The authors also need to present the important results from the EU MILLENNIUM and ADVICE projects, which deal with documentary and early instrumental data from the region under consideration. In addition, authors should place more emphasis on other publications dealing with single years or longer drought periods within the study period that are not cited and discussed, e.g. Pauling et al. 2006, Trigo et al. 2009; Smerdon et al. 2017 et al. and the references therein. It is important to clearly state what has been done so far, how the new data is new and/or different and explain how this study goes beyond the current state of research and where the information is complementary and confirms recent findings. The authors have mentioned important publications by Domínguez-Castro and Tejedor, but they need to be addressed and compared in more detail.
It is not entirely clear how the authors compare document-based drought information (which is descriptive and feeds into an index which is subjective) and the index-based information in the instrumental period, which is based on observations. The two sections on documentary information and instrumental data need to be better linked and compared. Currently, the two parts are separate and need to be better linked. The discussion section could be merged with the results to improve readability and generally shorten the text. How is it possible to compare the index from the past with the differently derived index from meteorological observations? In both cases there are uncertainties that should be mentioned and discussed, and caution is also needed when interpreting results from different time periods.
Information on the climatology of the Mediterranean: The Mediterranean region does indeed receive considerable precipitation amounts in winter. This is not correctly mentioned in the manuscript and a generally better description of the current spatio-temporal precipitation distribution for the area is required.
The sections labelled "state of the art" do not convey the actual state of the art to the reader, but are too short, sometimes confusing because they do not cite the correct sources and/or do not include the primary sources, and the explanations are too simplified.
Information on recent findings and current understanding of climatic conditions, the role of forcing factors (solar, land use, volcanoes, CO2, etc.) and regional impacts of tropical volcanoes during the period under study also need to be more carefully updated and analysed. At the regional and subcontinental level, there are also many new findings that are important for understanding past drought events in north-eastern Spain. For example, the statistical and dynamical explanations for the seasonal and regional climate impacts (temperature, precipitation, circulation) following strong tropical volcanic eruptions are discussed in Fischer et al. 2007 and others. Fischer et al. was cited, but the content and reference to this study need to be emphasised more strongly. For Tambora in particular, the following references should be cited and used for comparison: Raible et al. 2015; Luterbacher and Pfister, 2015; Luterbacher et al. 2016 and Trigo et al. 2009 for the case of Tambora and regional drought in Iberia.
In addition, the physical relationships associated with the occurrence of drought in the past and their comparison with the current situation are presented. The article suggests that the changes in solar radiation during the Dalton Minimum are relevant, but no evidence is provided for a possible link between the solar radiation and drought. Personally, I do not believe that there is a physical mechanism linking the changes in solar radiation during the dry season to hydroclimatic phenomena at the local scale during certain seasons. The authors could make a more convincing case if they find natural variations in their data, or if the extent and intensity of local to regional drought patterns in certain years/periods is related to strong tropical eruptions, and if so, justify this.
Generally, the results section is very long and can be shortened by at least 25%.
References mentioned above:
Luterbacher, J., and Pfister, C., 2015: The year without a summer. Nature Geosci., 8, 246-248.
Pauling, A., Luterbacher, J., Casty, C., and Wanner, H., 2006: 500 years of gridded high-resolution precipitation reconstructions over Europe and the connection to large-scale circulation. Clim. Dynam. 26, 387-405.
Raible, C.C., Brönnimann, S., Auchmann, R., Brohan, P., Frölicher, T., Graf, H.F., Jones, P., Luterbacher, J., Muthers, S., Robock, A., Self, S., Sudrajat, A., Timmreck, C., and Wegmann, M., 2016: Tambora 1815 as a test case for high impact volcanic eruptions: Earth system effects. Wires Clim Change, 7, 569-589.
Smerdon, J.E., et al. 2017: Comparing data and model estimates of hydroclimate variability and change over the Common Era. Clim Past. 13, 1851–1900.
Trigo, R.M., Vaquero, J.M., Alcoforado, M.J., Barriendos, M., Taborda, J., Garcia-Herrera, R., and Luterbacher, J., 2009: Iberia in 1816, the year without summer. Int. J. Climatol., 29, 99–115.
Citation: https://doi.org/10.5194/egusphere-2023-2177-RC1 -
AC2: 'Reply on RC1', Josep Barriendos, 02 Mar 2024
Answer:
The authors express their gratitude for the suggestions made in this review by Referee #1. In the following text, we provide a detailed answer to all those comments that have been suggested by Referee #1.
Comment:
The authors present new high-resolution hydrometeorological and climatological data for north-eastern Spain for the period of the late 18th and early 19th centuries. This is important because the authors, who are very experienced in the field of regional historical climatology, provide new insights from reliable and highly relevant documentary evidence, so-called rogations, and place them in the context of today's drought conditions. The topic is therefore suitable for the journal and the reviewer is very much in favour of publishing the article after revision. However, some sections need to be reconsidered and rewritten. Currently, the paper is rather descriptive and speculative and needs more scientific basis and arguments for the conclusions the authors draw.
In addition, the manuscript needs extensive English editing.
Answer:
Thank you for this suggestion. Along with the rewritten paragraphs of the introduction and results, the other sections (methodology and discussion) have been edited to improve the language used.
Comment:
Below are some general comments that should be taken into account. They are not in any particular order and should be addressed in addition to the general statements above:
Abstract/conclusions:
These sections are rather general and duplicate text from other sections. Both sections need to be refocused when revising the paper.
Answer:
We understand that it is not convenient to reiterate content in an academic text. In this regard, we have rewritten the abstract and conclusions to make them more normative and to show only the most significant aspects of the work. Nevertheless, these sections still contain information similar to other sections, in order to give a complete synthesis view of the work.
Comment:
Introduction:
This section should include the drought definitions from the IPCC's latest AR6.
Answer:
Thank you for this suggestion. We consider it very convenient.
We agree to add the IPCC definition to the definitions already made to the concept of drought. The definition in the IPCC Glossary AR6 of 2022 has been used. The definitions that appear in this glossary for the different types of droughts have also been added.
Comment:
Further, this section and the objectives do not yet provide the reader with the necessary justification as to why this paper is necessary, what has been published on this topic so far and what new elements the authors intend to cover in this publication. These sections therefore need to be better structured and reflect the state of research in this area.
Answer:
We appreciate the suggestion to strengthen the justification of the article. The introduction section with the justification has been extensively modified to add more references and make the section clearer.
Comment:
The section on the current state of historical drought research is not complete. The authors also need to present the important results from the EU MILLENNIUM and ADVICE projects, which deal with documentary and early instrumental data from the region under consideration.
Answer:
References derived from these projects have been accessed and their results have been considered in the text. Especially from the MILLENIUM project which offers more recent results.
Comment:
In addition, authors should place more emphasis on other publications dealing with single years or longer drought periods within the study period that are not cited and discussed, e.g. Pauling et al. 2006, Trigo et al. 2009; Smerdon et al. 2017 et al. and the references therein. It is important to clearly state what has been done so far, how the new data is new and/or different and explain how this study goes beyond the current state of research and where the information is complementary and confirms recent findings. The authors have mentioned important publications by Domínguez-Castro and Tejedor, but they need to be addressed and compared in more detail.
Answer:
We have consulted and incorporated more references to justify the interest of the work and to place it in the context of rainfall variability at different time scales and with the use of different sources of information.
Comment:
It is not entirely clear how the authors compare document-based drought information (which is descriptive and feeds into an index which is subjective) and the index-based information in the instrumental period, which is based on observations. The two sections on documentary information and instrumental data need to be better linked and compared. Currently, the two parts are separate and need to be better linked. The discussion section could be merged with the results to improve readability and generally shorten the text. How is it possible to compare the index from the past with the differently derived index from meteorological observations? In both cases there are uncertainties that should be mentioned and discussed, and caution is also needed when interpreting results from different time periods.
Answer:
We started with two very different blocks of information (historical documentary proxy and instrumental records). The origin and treatment applied to each has been explained. Up to this point, the treatment has been separated. However, the results obtained in the pluviometric variability of the historical proxy and the instrumental record have been analysed jointly for the reconstruction and characterisation of the anomaly under study (See figure 8 of the revised manuscript, in the discussion of the results). Statistical correlations have also been obtained between both sets of information. The results and conclusions of the work are based on the simultaneous behaviour of both types of information.
We do not consider that the results and the discussion have to be put together as they perform different functions.
Comment:
Information on the climatology of the Mediterranean: The Mediterranean region does indeed receive considerable precipitation amounts in winter. This is not correctly mentioned in the manuscript and a generally better description of the current spatio-temporal precipitation distribution for the area is required.
Answer:
In the introduction, winter in the Mediterranean climate is presented as a season of low precipitation. In the text, the regional varieties of the Mediterranean climate of the Spanish Mediterranean coast have been clarified in relation to the seasonal distribution of precipitation. Basically, two varieties are distinguished according to the prominence of spring or winter as a secondary peak of annual precipitation. All of this is based on the premise of the main amount of rainfall in the autumn months (mainly October and November) and the virtual absence of rainfall in summer, a defining feature of climates with a subtropical link (subtropical cell of the Azores), such as the Mediterranean climate type. This part of the text has been modified to be clearer and to mention that rainfall is low on average compared to the other rainy seasons (autumn and spring).
Comment:
The sections labelled "state of the art" do not convey the actual state of the art to the reader, but are too short, sometimes confusing because they do not cite the correct sources and/or do not include the primary sources, and the explanations are too simplified.
Answer:
This section has been reinforced and completed in order to be more specific and to add recent references to authors who have studied droughts in Spain using historical data. Its name has also been modified to focus it on the subject under study.
Comment:
Information on recent findings and current understanding of climatic conditions, the role of forcing factors (solar, land use, volcanoes, CO2, etc.) and regional impacts of tropical volcanoes during the period under study also need to be more carefully updated and analysed. At the regional and subcontinental level, there are also many new findings that are important for understanding past drought events in north-eastern Spain. For example, the statistical and dynamical explanations for the seasonal and regional climate impacts (temperature, precipitation, circulation) following strong tropical volcanic eruptions are discussed in Fischer et al. 2007 and others. Fischer et al. was cited, but the content and reference to this study need to be emphasised more strongly. For Tambora in particular, the following references should be cited and used for comparison: Raible et al. 2015; Luterbacher and Pfister, 2015; Luterbacher et al. 2016 and Trigo et al. 2009 for the case of Tambora and regional drought in Iberia.
Answer:
Thank you for this suggestion. These references to the effects of the Tambora eruption have been added.
Comment:
In addition, the physical relationships associated with the occurrence of drought in the past and their comparison with the current situation are presented. The article suggests that the changes in solar radiation during the Dalton Minimum are relevant, but no evidence is provided for a possible link between the solar radiation and drought. Personally, I do not believe that there is a physical mechanism linking the changes in solar radiation during the dry season to hydroclimatic phenomena at the local scale during certain seasons. The authors could make a more convincing case if they find natural variations in their data, or if the extent and intensity of local to regional drought patterns in certain years/periods is related to strong tropical eruptions, and if so, justify this.
Answer:
We have already specified in the text that there is only a chronological coincidence between the solar minimum and the drought episodes studied in the work. We have stressed that there is no cause-effect relationship between the two phenomena.
Comment:
Generally, the results section is very long and can be shortened by at least 25%.
Answer:
We appreciate the advice to shorten the results section. The text has been edited and some of the figures have been modified and deleted in order to reduce the length of this section.
Comment:
References mentioned above:
Luterbacher, J., and Pfister, C., 2015: The year without a summer. Nature Geosci., 8, 246-248.
Pauling, A., Luterbacher, J., Casty, C., and Wanner, H., 2006: 500 years of gridded high-resolution precipitation reconstructions over Europe and the connection to large-scale circulation. Clim. Dynam. 26, 387-405.
Raible, C.C., Brönnimann, S., Auchmann, R., Brohan, P., Frölicher, T., Graf, H.F., Jones, P., Luterbacher, J., Muthers, S., Robock, A., Self, S., Sudrajat, A., Timmreck, C., and Wegmann, M., 2016: Tambora 1815 as a test case for high impact volcanic eruptions: Earth system effects. Wires Clim Change, 7, 569-589.
Smerdon, J.E., et al. 2017: Comparing data and model estimates of hydroclimate variability and change over the Common Era. Clim Past. 13, 1851–1900.
Trigo, R.M., Vaquero, J.M., Alcoforado, M.J., Barriendos, M., Taborda, J., Garcia-Herrera, R., and Luterbacher, J., 2009: Iberia in 1816, the year without summer. Int. J. Climatol., 29, 99–115.Citation: https://doi.org/10.5194/egusphere-2023-2177-AC2
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AC2: 'Reply on RC1', Josep Barriendos, 02 Mar 2024
-
RC2: 'Comment on egusphere-2023-2177', Anonymous Referee #2, 15 Jan 2024
The manuscript titled 'High-resolution reconstruction of drought episodes during the Dalton Solar Minimum (1790–1830) in the Spanish Mediterranean Basin' by Josep Barriendos et al presents an interesting study on droughts in the Spanish Mediterranean coast in the early decades of the 19th century. Despite the study appearing interesting and useful for the climatological community, it has significant issues that clearly prevent its publication in its current form. I will describe below the most important problems and some specific issues.
1. Main problems
1.1. The solar connection
The unifying and guiding element of this study is the Dalton Minimum. This is emphasized in both the title, the abstract, and the main text. However, this element is entirely overlooked in the development of the analysis and discussion presented in this manuscript. This is a serious issue in presentation or explanation, given that the relationships between solar activity and Earth's climate have been a subject of contentious debates in both scientific and socio-political spheres. I am confident that authors, editors, and referees do not wish for this manuscript to be featured in the press with the headline 'a scientific study proves that the Sun causes droughts in Spain.' Yet, that is the impression it currently gives. Therefore, the manuscript needs substantial rewriting to address this issue.
Firstly, the authors need to explain what the Dalton Minimum is. In the last sentence of the manuscript, the authors state: 'In the light of the good results obtained from the combination of these two sources of climatic information, a future line of research for the Dalton Solar Minimum and other relevant climatic periods would consist of combining the historical data with data from other climatic proxies (especially dendrochronology) and instrumental pressure series, which would allow the understanding of the atmospheric processes on a synoptic scale that directly explain the most severe episodes of drought.' This is entirely incorrect from a conceptual standpoint since the Dalton Minimum is a significant solar episode (not climatic), just as the Little Ice Age (LIA) is not a solar phenomenon but a climatic one.
Indeed, the Dalton Minimum corresponds to solar cycles 5 and 6, although some authors also include solar cycle 7. Two recent studies on the topic indicate the period 1797-1827 (Hayakawa et al., 2020a, 2020b). It is crucial to note that studies in solar physics associate the Dalton Minimum with a Gleissberg cycle minimum (Usoskin et al., 2007; Feynman & Ruzmaikin, 2011) and not with a 'Grand Minimum' of solar activity like the Maunder Minimum (1645-1715) (Usoskin et al., 2015). It is of critical importance because solar physicists and geophysicists do not consider the Dalton Minimum as a 'Grand Minimum' of solar activity. An update on solar activity over the last four centuries can be found in Clette et al. (2023).
The manuscript barely mentions another major climatic forcing factor, which is volcanic forcing. However, at least 60 volcanic eruptions occurred between 1791 and 1830 with a Volcanic Explosivity Index (VEI) ≥3, including 17 with VEI ≥ 4 (Global Volcanism Program, 2013). This should have produced clear climatic signals (Schmidt et al., 2018; Fang et al., 2023).
1.2. Spatial representativeness of the data
The authors use the AMARNA database. In particular, water deficits are obtained from the records of "pro pluvia" rogation ceremonies. Table 2 lists the classification system of the AMARNA database and Figure 6 show in a Table the number of positive ERE cases (FF, PF, PR, SS) and negative ERE cases (DR) for the Spanish river basins in the period 1790-1830 (named by authors "Dalton Solar Minimum").
In this unnumbered table that appears in Figure 6, a brutal difference between the Mediterranean and Atlantic basins can be seen. For example, while in the CIC basin there are a total of 741 cases (223 positive cases and 518 negative cases), there are six basins with a total number of cases less than 10. This brutal asymmetry in the number of cases prevents any spatial analysis of the data as a whole (as is the case in a large part of the manuscript).
To try to explain this critical problem a little more, we can focus our attention on Figure 8, which shows the spatial distribution of "Towns with more than 50 cases of drought". Evidently, Mediterranean cities appear (where there are many cases) and the city of Seville (with 161 total cases in the database for the period studied). And obviously, the cities of the Atlantic zone do not appear because, in general, there are not even 50 total cases in the database for the entire period and the entire basin. The conclusion is that this type of analysis does not contribute anything new. Unfortunately, this manuscript is plenty of this kind of problem.
1.3. Local analysis, global conclusion
The authors also use the Barcelona precipitation series for their analysis. But this implies that the results obtained are local and, often, in the manuscript these results are shown as global for the Mediterranean basin. This creates enormous uncertainties in any reader who knows the differences in the modern precipitation regimes of Barcelona, Murcia, or Malaga, for example.
This could be addressed by analyzing more early instrumental series. Unfortunately, I think that there are no such early precipitation series in the Spanish Mediterranean. However, some long series (even if it does not cover the first half of the 19th century) could be used to check the results obtained for the last 150 years.
On the other hand, there is an enormous amount of literature on droughts on the Spanish Mediterranean coast in recent decades and it seems that the authors of this manuscript have not been able to take advantage of this enormous amount of knowledge to make the analysis of the series of historical precipitation of Barcelona.
A final comment on the precipitation series used is obligatory. The authors have concatenated several precipitation series from different stations in Barcelona for the most modern period. This needs a clear justification for the reader who expects there to be a reference series in the city from the Spanish or Catalan meteorological agency without requiring so many station changes (which raise suspicions about the quality of the data).
2. Other problems
a. Section 1.2. State of the Art of Historical Droughts Studies
This section reviews the development of “Historical Droughts Studies” but surprisingly does not include the most recent works on the subject. Obviously, I do not intend for all recent work to be included. But I consider that there are very significant recent works that should be included here. A notable example is the creation of an international database of rogation dates (Domínguez-Castro et al, 2021), which provides the international scientific community with more than 3,500 rogation celebration dates for 11 countries in recent centuries. Likewise, it could be interesting to put in this context some recent works on rogations both outside (Garza-Merodio, 2017; Garnier, 2019) and within Iberia (Fragoso et al, 2018; Bravo-Paredes, 2020).
b. Quality of Figures
A large number of figures present important deficiencies such as not having “labels” for the horizontal or vertical axes, which makes the reader's interpretation extremely difficult. There are also figures that include tables… This is not very standard in scientific publications.
c. Writting problems
My native language is not English, but it seems clear that the writing of this manuscript needs to improve a lot. Some expressions are Spanish phrases literally translated into English that are probably not understood by many readers. Furthermore, the order of words in sentences sometimes significantly affects their meaning, such as “Only three drought episodes are notable outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24)” which should be “Only three noteworthy drought episodes are outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24). There are also single unconnected words in some places. For example, in the caption of figure 6 it reads: “[…] river basins. Dalton Solar Minimum (1790-1830). A list […]”
d. Unrecognized work
I consider that the authors of this manuscript do not recognize and do not give sufficient credit to research groups that work on droughts (historical and modern) in Iberia. A notable example is that Ricardo Trigo's pioneering work on the year without a summer is not cited (Trigo et al, 2009). Any serious work that aims to study the climate of a region of Iberia in the first decades of the 19th century must compare its results with this pioneering work and must show how his work relates to this study. Something similar occurs with the great achievements obtained by Sergio Vicente-Serrano and his group in the area of droughts, including their characterization with different indices. I do not understand that any results shown in this manuscript have a connection with the relevant works published by this research group. If the authors managed to connect their analysis and results with this type of work, they would gain strength and support for their ideas.
3. Conclusion
In short, although I think that the severe droughts of the first decades of the 19th century detected by the authors should be studied, the problems that I detect in this manuscript clearly prevent its publication.
I think the general approach is wrong and dangerous. You cannot frame this study in the Dalton Minimum and then completely ignore solar forcing. This approach must be more rigorous and detailed. On the other hand, I detect important problems both in the data from documents (lack of spatial homogeneity) and in the instrumental data (lack of global representativeness). This clearly affects both the analyzes carried out and the results, as I have briefly shown above.
Finally, the problems are so deep that I recommend rejecting this article for publication, despite the interest of this topic of study.
References
Bravo-Paredes, N., et al (2020) Pro-pluvia rogation ceremonies in Extremadura (Spain): Are they a good proxy of winter NAO? Atmosphere (Basel), 11(3), 282.
Clette et al. (2023) “Recalibration of the Sunspot Number: Status Report” Solar Physics 298, 44.
Hayakawa, Hisashi et al. (2020a) "Thaddäus Derfflinger's Sunspot Observations during 1802–1824: A Primary Reference to Understand the Dalton Minimum", in The Astrophysical Journal, 890, 98.
Hayakawa, Hisashi et al. (2020b) "The Solar Corona during the Total Eclipse on 1806 June 16: Graphical Evidence of the Coronal Structure during the Dalton Minimum", The Astrophysical Journal, 900, 114.
Fang, S.-W., Sigl, M., Toohey, M., Jungclaus, J., Zanchettin, D., & Timmreck, C. (2023). The role of small to moderate volcanic eruptions in the early 19th century climate. Geophysical Research Letters, 50, e2023GL105307.
Feynman, J., Ruzmaikin, A. (2011) “The Sun's Strange Behavior: Maunder Minimum or Gleissberg Cycle?” Solar Physics, Volume 272, Issue 2, article id.351
Fragoso, M., Carraça, M. D. G. & Alcoforado, M. J. (2018) Droughts in Portugal in the 18th century: A study based on newly found documentary data. Int. J. Climatol. 38, 5522.
Garnier, E. (2019) Historic Drought from archives: Beyond the Instrumental Record. in Drought Science and Policy (ed. Iglesias A., Assimacopoulos D. & Van Lanen, H. A. J.) 45–67 (Wiley-Blackwell).
Garza-Merodio, G. G. (2017) Variabilidad climática en México a través de fuentes documentales (siglos XVI al XIX). (Instituto de Geografía, Universidad Nacional Autónoma de México).
Global Volcanism Program (2013). Global volcanism program. Volcanoes of the World. https://doi.org/10.5479/si.GVP.VOTW4-2013
Schmidt, A., Mills, M. J., Ghan, S., Gregory, J. M., Allan, R. P., Andrews, T., et al. (2018). Volcanic radiative forcing from 1979 to 2015. Journal of Geophysical Research: Atmospheres, 123(22), 12491–12508.
Trigo et al. (2009) “Iberia in 1816, the year without a summer” International Journal of Climatology 29, 99.
Usoskin, I. G.; Solanki, S. K.; Kovaltsov, G. A. (2007) Grand minima and maxima of solar activity: new observational constraints, Astronomy and Astrophysics, Volume 471, Issue 1, pp.301-309.
Usoskin et al. (2015) “The Maunder minimum (1645–1715) was indeed a Grand minimum: A reassessment of multiple datasets” Astronomy & Astrophysics 581, A95.
Citation: https://doi.org/10.5194/egusphere-2023-2177-RC2 -
AC3: 'Reply on RC2', Josep Barriendos, 02 Mar 2024
Answer:
The authors express their gratitude for the suggestions made in this review by Referee #2. In the following text, we provide a detailed answer to all those comments that have been suggested by Referee #2.
Comment:
The manuscript titled 'High-resolution reconstruction of drought episodes during the Dalton Solar Minimum (1790–1830) in the Spanish Mediterranean Basin' by Josep Barriendos et al presents an interesting study on droughts in the Spanish Mediterranean coast in the early decades of the 19th century. Despite the study appearing interesting and useful for the climatological community, it has significant issues that clearly prevent its publication in its current form. I will describe below the most important problems and some specific issues.
1. Main problems
1.1. The solar connection
The unifying and guiding element of this study is the Dalton Minimum. This is emphasized in both the title, the abstract, and the main text. However, this element is entirely overlooked in the development of the analysis and discussion presented in this manuscript. This is a serious issue in presentation or explanation, given that the relationships between solar activity and Earth's climate have been a subject of contentious debates in both scientific and socio-political spheres. I am confident that authors, editors, and referees do not wish for this manuscript to be featured in the press with the headline 'a scientific study proves that the Sun causes droughts in Spain.' Yet, that is the impression it currently gives. Therefore, the manuscript needs substantial rewriting to address this issue.
Answer:
The intention of the authors was not to relate any solar phenomenon to terrestrial climate variability, as this is a research field that is still open and has many research questions to be solved. Indeed, accepting the reviewer's point of view, we want to adjust the definition of our work by radically changing the title of the study and the meaning of the expressions between the Dalton Solar Minimum and the climate variability we describe. We have proposed a general temporal definition ("Early 19th Century"). Our study does NOT intend to analyse the Solar Dalton Minimum or any other interrelationship with phenomena in the Earth's atmosphere that are still under investigation. Only in subsequent research, when we have a temporal sequence with more similar drought episodes, will we be in a position to work with specialists to provide insights into episodes or anomalies that may be associated with these drought events.
Comment:
Firstly, the authors need to explain what the Dalton Minimum is. In the last sentence of the manuscript, the authors state: 'In the light of the good results obtained from the combination of these two sources of climatic information, a future line of research for the Dalton Solar Minimum and other relevant climatic periods would consist of combining the historical data with data from other climatic proxies (especially dendrochronology) and instrumental pressure series, which would allow the understanding of the atmospheric processes on a synoptic scale that directly explain the most severe episodes of drought.' This is entirely incorrect from a conceptual standpoint since the Dalton Minimum is a significant solar episode (not climatic), just as the Little Ice Age (LIA) is not a solar phenomenon but a climatic one.
Answer:
We fully agree with your comment on the treatment of the Dalton Solar Minimum and the climate anomaly under study. We have, according to your criterion and that of the other reviewers, correctly redefined this erroneous interrelation. We regret having expressed this misconception and have corrected it both in the contents of the manuscript and in the title itself. Precisely in line with this review, it can be understood that we do not deal in detail with the characteristics of the Dalton Solar Minimum, since this is not our thematic area of expertise.
Our intention in using the concept of the Dalton Solar Minimum was only to provide the reader with a temporal location of our work using as a reference another natural phenomenon that occurs in a similar chronology. Our approach had no unscientific intention, but rather used a pattern already employed by the scientific community in historical climatology in which a solar minimum is compared with climatic anomalies: Frenzel, B. (editor), 1994. Within this work there are several articles whose titles express the study of climatic anomalies "during the late Maunder Minimum (1675-1715)".
Comment:
Indeed, the Dalton Minimum corresponds to solar cycles 5 and 6, although some authors also include solar cycle 7. Two recent studies on the topic indicate the period 1797-1827 (Hayakawa et al., 2020a, 2020b). It is crucial to note that studies in solar physics associate the Dalton Minimum with a Gleissberg cycle minimum (Usoskin et al., 2007; Feynman & Ruzmaikin, 2011) and not with a 'Grand Minimum' of solar activity like the Maunder Minimum (1645-1715) (Usoskin et al., 2015). It is of critical importance because solar physicists and geophysicists do not consider the Dalton Minimum as a 'Grand Minimum' of solar activity. An update on solar activity over the last four centuries can be found in Clette et al. (2023).
Answer:
We are grateful for these explanations, but the criticism regarding the use of the Dalton Solar Minimum concept is accepted and we do not intend in this work to discuss any aspect that relates the climatic variability of pluviometric extremes with the behaviour of solar radiation. We omit the introduction of details on the behaviour of solar radiation because they are beyond the scope of this paper.
Comment:
The manuscript barely mentions another major climatic forcing factor, which is volcanic forcing. However, at least 60 volcanic eruptions occurred between 1791 and 1830 with a Volcanic Explosivity Index (VEI) ≥3, including 17 with VEI ≥ 4 (Global Volcanism Program, 2013). This should have produced clear climatic signals (Schmidt et al., 2018; Fang et al., 2023).
Answer:
In this aspect of volcanic activity, we have followed the criteria for the most significant explosive volcanic eruptions and their possible relationship with climatic anomalies that appear in a doctoral thesis working within the geographical field of this study (Prohom, 2003).
In any case, we are grateful for the detailed information provided and we include it in the text because it improves the quality of the text (See lines 240 to 243 of the revised manuscript).
Comment:
1.2. Spatial representativeness of the data
The authors use the AMARNA database. In particular, water deficits are obtained from the records of "pro pluvia" rogation ceremonies. Table 2 lists the classification system of the AMARNA database and Figure 6 show in a Table the number of positive ERE cases (FF, PF, PR, SS) and negative ERE cases (DR) for the Spanish river basins in the period 1790-1830 (named by authors "Dalton Solar Minimum").
In this unnumbered table that appears in Figure 6, a brutal difference between the Mediterranean and Atlantic basins can be seen. For example, while in the CIC basin there are a total of 741 cases (223 positive cases and 518 negative cases), there are six basins with a total number of cases less than 10. This brutal asymmetry in the number of cases prevents any spatial analysis of the data as a whole (as is the case in a large part of the manuscript).To try to explain this critical problem a little more, we can focus our attention on Figure 8, which shows the spatial distribution of "Towns with more than 50 cases of drought". Evidently, Mediterranean cities appear (where there are many cases) and the city of Seville (with 161 total cases in the database for the period studied). And obviously, the cities of the Atlantic zone do not appear because, in general, there are not even 50 total cases in the database for the entire period and the entire basin. The conclusion is that this type of analysis does not contribute anything new. Unfortunately, this manuscript is plenty of this kind of problem.
Answer:
We understand the criticism regarding the great difference in the number of episodes and cases between the Mediterranean and Atlantic basins. In our approach, we do not intend to analyse drought in all of Spain. The title already makes it clear that the core of the work focuses on the Mediterranean basin of the Iberian Peninsula. For us, the material available on the Atlantic basin only constitutes a reinforcement or complement to the analysis of the core material from the Mediterranean area.
In response to your comment, we accept that this aspect was not sufficiently explained in the section on sources and methods and we proceed to introduce an explanatory paragraph in the text (See lines 490 to 495 of the revised manuscript).
Comment:
1.3. Local analysis, global conclusion
The authors also use the Barcelona precipitation series for their analysis. But this implies that the results obtained are local and, often, in the manuscript these results are shown as global for the Mediterranean basin. This creates enormous uncertainties in any reader who knows the differences in the modern precipitation regimes of Barcelona, Murcia, or Malaga, for example.
This could be addressed by analyzing more early instrumental series. Unfortunately, I think that there are no such early precipitation series in the Spanish Mediterranean. However, some long series (even if it does not cover the first half of the 19th century) could be used to check the results obtained for the last 150 years.
Answer:
We understand the limitation that exists in the study of this type of hydrometeorological anomalies with respect to the availability of early instrumental series. In our work we have used the material available for the period under study and, to date, we do not know of any other instrumental series for the period 1790-1830. We only have some short time series for the city of Valencia that we are in the process of digitising, but without the precipitation variable. On the Atlantic side, Madrid covers this period, but without precipitation records. At least, in the archival work we have done, this variable does not appear. Finally, the observations of the Spanish Navy in Cadiz and the Royal Navy in Gibraltar provide precipitation records, but at low resolution or with important gaps. We accept that the use of a single instrumental series can be considered a localism, but we have worked with the best possible material and in any case the comparison of instrumental and historical records has seemed to us to be a correct procedure for the characterisation of drought episodes.
Nevertheless, given the limited instrumental series available, we have qualified the references to the Barcelona series and its possible value as a series to show regional anomalies. In addition, we have added a paragraph on this possible bias in the available data (See lines 404 to 407 of the revised manuscript). Finally, it should be noted that the study refers to the Spanish Mediterranean basins, but with a special focus on the basins of Catalonia. In this sense, the Barcelona instrumental series does show spatio-temporally coherent variability patterns at the level of these basins.
Comment:
On the other hand, there is an enormous amount of literature on droughts on the Spanish Mediterranean coast in recent decades and it seems that the authors of this manuscript have not been able to take advantage of this enormous amount of knowledge to make the analysis of the series of historical precipitation of Barcelona.
Answer:
The present work uses the historical materials with which previous studies on climate variability in historical climatology have been developed for Barcelona and Catalonia as a whole. In this regard, we have consulted references such as Dominguez-Castro et al., 2012, and others which have been added in section 1.2 Historical Droughts Studies in Spain.
Until now, the works developed used numerical indices at low temporal resolution, whereas in the present work we have taken a new approach to analysis using the historical material at daily and monthly resolutions.
Comment:
A final comment on the precipitation series used is obligatory. The authors have concatenated several precipitation series from different stations in Barcelona for the most modern period. This needs a clear justification for the reader who expects there to be a reference series in the city from the Spanish or Catalan meteorological agency without requiring so many station changes (which raise suspicions about the quality of the data).
Answer:
We fully accept this criticism regarding the description of the different sections of the Barcelona precipitation series. We understand that over the last 240 years this series have had very different locations and observation conditions. To show the reader these details, we introduce some explanatory paragraphs in section 2.1. detailing the basic characteristics of both the sections used in the Prohom et al., 2016 paper and in the 2014-2022 update section (See lines 409 to 421 of the revised manuscript).
Comment:
2. Other problems
a. Section 1.2. State of the Art of Historical Droughts Studies
This section reviews the development of “Historical Droughts Studies” but surprisingly does not include the most recent works on the subject. Obviously, I do not intend for all recent work to be included. But I consider that there are very significant recent works that should be included here. A notable example is the creation of an international database of rogation dates (Domínguez-Castro et al, 2021), which provides the international scientific community with more than 3,500 rogation celebration dates for 11 countries in recent centuries. Likewise, it could be interesting to put in this context some recent works on rogations both outside (Garza-Merodio, 2017; Garnier, 2019) and within Iberia (Fragoso et al, 2018; Bravo-Paredes, 2020).
Answer:
We are grateful for the effort made in referencing recent works on historical droughts, which have been included. In addition to these indications, we have also taken good account of the indications of the other reviewers. With all this, we have drafted some additional paragraphs to be introduced in the State of the Art, which we believe considerably improve its content (See lines 294 to 306 of the revised manuscript). Thank you again.
Comment:
b. Quality of Figures
A large number of figures present important deficiencies such as not having “labels” for the horizontal or vertical axes, which makes the reader's interpretation extremely difficult. There are also figures that include tables… This is not very standard in scientific publications.
Answer:
We have addressed this aspect by improving almost all the figures, following the indications of the 3 reviewers at all times. We are grateful for the effort made by the reviewers, especially in this aspect.
Comment:
c. Writting problems
My native language is not English, but it seems clear that the writing of this manuscript needs to improve a lot. Some expressions are Spanish phrases literally translated into English that are probably not understood by many readers. Furthermore, the order of words in sentences sometimes significantly affects their meaning, such as “Only three drought episodes are notable outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24)” which should be “Only three noteworthy drought episodes are outside of the DSM: 1877-1879 (Nr. 14), 2015-2018 (Nr. 23) and 2021-2022 (Nr. 24). There are also single unconnected words in some places. For example, in the caption of figure 6 it reads: “[…] river basins. Dalton Solar Minimum (1790-1830). A list […]”
Answer:
A detailed review has been carried out and we believe that a substantial improvement has been made in this area.
Comment:
d. Unrecognized work
I consider that the authors of this manuscript do not recognize and do not give sufficient credit to research groups that work on droughts (historical and modern) in Iberia. A notable example is that Ricardo Trigo's pioneering work on the year without a summer is not cited (Trigo et al, 2009). Any serious work that aims to study the climate of a region of Iberia in the first decades of the 19th century must compare its results with this pioneering work and must show how his work relates to this study. Something similar occurs with the great achievements obtained by Sergio Vicente-Serrano and his group in the area of droughts, including their characterization with different indices. I do not understand that any results shown in this manuscript have a connection with the relevant works published by this research group. If the authors managed to connect their analysis and results with this type of work, they would gain strength and support for their ideas.
Answer:
References on Ricardo Trigo have been conveniently included. His work, in which some of the co-authors of this paper participated, focuses on a very specific period and therefore we had not considered its inclusion from the beginning. In the revised version, this reference and others by the same author have been included, following the reviewer's suggestions, in this commentary and in previous comments (See lines 173 to 174 of the revised manuscript).
With respect to the work of Sergio Vicente-Serrano and his research group, we are familiar with their work. In this regard, we have used their methodologies and have referenced them appropriately in the revised version of the paper and in line with the response to previous suggestions. We have also referenced some works of members of that research group that used documentary sources, although they are already known materials elaborated by one of the co-authors of the present work. Our contribution in this work is based on a singularized approach for drought episodes in high temporal resolution that uses much more defined or concrete materials.
Comment:
3. Conclusion
In short, although I think that the severe droughts of the first decades of the 19th century detected by the authors should be studied, the problems that I detect in this manuscript clearly prevent its publication.
I think the general approach is wrong and dangerous. You cannot frame this study in the Dalton Minimum and then completely ignore solar forcing. This approach must be more rigorous and detailed. On the other hand, I detect important problems both in the data from documents (lack of spatial homogeneity) and in the instrumental data (lack of global representativeness). This clearly affects both the analyzes carried out and the results, as I have briefly shown above.
Finally, the problems are so deep that I recommend rejecting this article for publication, despite the interest of this topic of study.
Answer:
We are extremely grateful for the contributions and review efforts of the three reviewers involved. We have accepted and integrated most of the criticisms and suggestions for improvement. We believe that the effort made by both parties has contributed to a substantial improvement in the quality of the manuscript. For this reason, we hope that the result and negative evaluation of the present work can change towards a positive evaluation.
Comment:
ReferencesBravo-Paredes, N., et al (2020) Pro-pluvia rogation ceremonies in Extremadura (Spain): Are they a good proxy of winter NAO? Atmosphere (Basel), 11(3), 282.
Clette et al. (2023) “Recalibration of the Sunspot Number: Status Report” Solar Physics 298, 44.Hayakawa, Hisashi et al. (2020a) "Thaddäus Derfflinger's Sunspot Observations during 1802–1824: A Primary Reference to Understand the Dalton Minimum", in The Astrophysical Journal, 890, 98.
Hayakawa, Hisashi et al. (2020b) "The Solar Corona during the Total Eclipse on 1806 June 16: Graphical Evidence of the Coronal Structure during the Dalton Minimum", The Astrophysical Journal, 900, 114.
Fang, S.-W., Sigl, M., Toohey, M., Jungclaus, J., Zanchettin, D., & Timmreck, C. (2023). The role of small to moderate volcanic eruptions in the early 19th century climate. Geophysical Research Letters, 50, e2023GL105307.
Feynman, J., Ruzmaikin, A. (2011) “The Sun's Strange Behavior: Maunder Minimum or Gleissberg Cycle?” Solar Physics, Volume 272, Issue 2, article id.351
Fragoso, M., Carraça, M. D. G. & Alcoforado, M. J. (2018) Droughts in Portugal in the 18th century: A study based on newly found documentary data. Int. J. Climatol. 38, 5522.
Garnier, E. (2019) Historic Drought from archives: Beyond the Instrumental Record. in Drought Science and Policy (ed. Iglesias A., Assimacopoulos D. & Van Lanen, H. A. J.) 45–67 (Wiley-Blackwell).
Garza-Merodio, G. G. (2017) Variabilidad climática en México a través de fuentes documentales (siglos XVI al XIX). (Instituto de Geografía, Universidad Nacional Autónoma de México).
Global Volcanism Program (2013). Global volcanism program. Volcanoes of the World. https://doi.org/10.5479/si.GVP.VOTW4-2013
Schmidt, A., Mills, M. J., Ghan, S., Gregory, J. M., Allan, R. P., Andrews, T., et al. (2018). Volcanic radiative forcing from 1979 to 2015. Journal of Geophysical Research: Atmospheres, 123(22), 12491–12508.
Trigo et al. (2009) “Iberia in 1816, the year without a summer” International Journal of Climatology 29, 99.
Usoskin, I. G.; Solanki, S. K.; Kovaltsov, G. A. (2007) Grand minima and maxima of solar activity: new observational constraints, Astronomy and Astrophysics, Volume 471, Issue 1, pp.301-309.
Usoskin et al. (2015) “The Maunder minimum (1645–1715) was indeed a Grand minimum: A reassessment of multiple datasets” Astronomy & Astrophysics 581, A95.
Citation: https://doi.org/10.5194/egusphere-2023-2177-AC3
-
AC3: 'Reply on RC2', Josep Barriendos, 02 Mar 2024
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RC3: 'Comment on egusphere-2023-2177', Anonymous Referee #3, 23 Jan 2024
The article analyzes droughts in the Mediterranean coast of the Iberian Peninsula during the period 1790-1830, utilizing pro-pluvia rogations and early instrumental data from Barcelona. While experiments combining documentary sources and long instrumental data are inherently interesting, this article, in its current form, lacks focus and is speculative, making it difficult to read. Additionally, the methods used are either unjustified or incorrect, and most of the conclusions are speculative, poorly supported by the results. The editing also lacks attention to detail, with figures lacking labels on axes, duplicate information in tables and figures, references that do not appear in the reference list (e.g., Morron 2020), and large parts of the text that are unnecessary or could be highly summarized for the paper's objectives
I will begin my review by addressing the main problems with the proposed objectives. In the abstract, the principal objective is stated as follows: 'The objective of this study is to analyze the occurrence and magnitude of extreme droughts, lasting more than a year, in Spain during the Dalton Solar Minimum period (1790-1830).' However, this objective differs slightly from the main objective expressed in section 1.3: 'Analyze the patterns of drought episodes that affected the Spanish Mediterranean Basin during the Dalton Solar Minimum between 1790 and 1830 using instrumental and historical sources.' Several issues arise in achieving this objective. Firstly, it is necessary to clearly define the study area based on the data used. In the abstract, the study area is Spain, while in section 1.3, it is the Spanish Mediterranean Basin. Upon reading the paper, it becomes apparent that the correct area of study should be the North Spanish Mediterranean Basin, as most of the information and the most homogenous records are from this area. Secondly, to achieve this objective it is mandatory to clearly define what is considered a drought episode, including its magnitude and duration (both for the instrumental and for the documentary period) . This clarity is lacking in the methodology.
Regarding the 'additional objectives':
- 'To qualitatively and quantitatively extend the AMARNA database on climate risks (Arxius Multidisciplinars per a l’Anàlisi del Risc Natural i Antròpic, from Catalan: Multidisciplinary Archives for the Analysis of Natural and Anthropogenic Risk) to incorporate droughts and different social processes linked to environmental impact in addition to hydrometeorological excesses (Tuset et al., 2022)': This objective stands out as one of the most significant contributions of the paper to the scientific community. It is crucial to provide a detailed description of the qualitative and quantitative improvements made to the AMARNA database. This includes specifics such as the number of new locations and dates of rogation ceremonies incorporated. Additionally, defining the Mediterranean locations covered by the database is essential for understanding the spatial pattern analysis attempted in the paper. The heterogeneity of available data may pose challenges to this analysis, so clarifying the extent and characteristics of the database is vital. It's also important to confirm if the database is publicly available and provide information on how it can be accessed, taking into account the data policy of NHESS (https://www.natural-hazards-and-earth-system-sciences.net/submission.html).
- 'To compile and describe the variability of extreme hydrometeorological events (torrential rainfall and droughts) in the Spanish Mediterranean Basin during the DSM': The utility of analyzing torrential rainfalls alongside the main objective focused on drought events is not clear. If the authors believe it is necessary, they should provide a more detailed explanation of why it adds value to the analysis and how it contributes to the main objective, avoiding introducing unnecessary noise.
- 'To characterize the drought episodes, analyzed from historical data and the instrumental precipitation series of Barcelona, considering their duration, extension, and severity in high resolution for the period analyzed': This objective seems to overlap with the main one. Regardless, it is necessary to clearly define how duration, extension, and severity are computed both from rogation ceremonies and from SPI and SPEI.
- 'To analyze the entire instrumental precipitation series of Barcelona spanning from X to Y in order to characterize periods of drought': I do not understand well the difference among this objective and the previous one. Whats mean 'X to Y??
Now I want to provide some comments order by the appearance in the text no by importance.
L. 43-58: The authors could discuss environmental droughts as a typology of drought, especially when considering their effects on the environment (L. 113).
L. 63-70: The explanation regarding pro pluvia rogations as a proxy for meteorological droughts is not entirely convincing. Previous studies have shown a clear link between rogations and agricultural processes, with seasonality tied to the agricultural calendar. I see the point of the authors about the daily resolution of the proxy, but I think that more evidences are required to affirm that rogation can be considered as a meteorological drought proxy. A comparison of precipitation in Barcelona and rogations at this location could shed light on this, and the authors should address the extrapolation of results to other climates more thoroughly.
L. 85-88: The statement that "the available knowledge focuses on very specific aspects during the instrumental period" is incorrect, and may be considered disrespectful to numerous authors who have worked on various aspects of droughts over the past decades. Citing studies like Van Loon & Van Lanen, 2012, does not support this assertion
L. 184-197: The review of historical droughts in the Iberian Peninsula appears outdated, with the latest papers cited being from 2013. Given the significant advances in the field over the last decade, the authors should update this section with more recent references.
L. 269-271: The use of two different stations to update the series of Barcelona until 2022 is mentioned, but the homogeneity of the final series is not analyzed. Since standardized drought indices are highly sensitive to inhomogeneities, it is crucial to analyze and address potential homogeneity issues in the updated series.
L. 273-319: In this section, the authors need to provide a clearer explanation of how the AMARNA database has been “qualitatively and quantitatively” improved. It is unclear how many new data have been added to the database and how the information processing has been enhanced compared to previous papers. Additionally, instead of Table 3, it may be more beneficial for the authors to present a map showing the locations with information on extremes during the studied period and the length of this records. This really allows the reader to understand the studied area.
L. 327-329: The authors seem unfamiliar with SPEI. Firstly the paper that describe the index is Vicente-Serrano et al. 2010 not Beguería et al. 2010 that describe a global database. The description of SPEI in the text is poor and lacks essential details as that the index try to replicate a balance of water in the atmosphere. The authors should specify how they computed atmospheric evaporative demand. Morover they must define and justify the temporal windows of the index and the threshold to consider drought conditions. These details significantly influence the results and should be thoroughly explained.
L. 377: The term "relative normality" is unclear. The period 1806-1812 is noted as anomalous, due to the scarcity of ERE events, both below the mean. This period coincides with the Peninsular War (1818-1814), raising the possibility of factors affecting the availability of documentary sources or record-keeping during wartime. The authors could provide information on the continuity and homogeneity of the documentary sources analyzed during the studied period to shed light on the observed low density of events.
Figures 2, 3, 4, and 5 contain similar information. Suggest summarizing this information in one or two figures.
L. 386: “This anomaly may be due to the fact that in this basin no specific campaigns for compiling drought information have been carried out” It is necessary to define in all areas if he low number of ERE are due to lack of data. This is manatory to understand figure 6.
Figure 7: Define "case of drought." The abstract mentions droughts lasting more than a year, but this doesn't seem possible here.
Figure 8: Explain how the "potential affected area" is computed.
L. 413: Clarify how the period 1812-1825 is possibly linked to Maldà Oscillation. Explain the nature of this link.
L. 466: Show plots with the severity and duration of droughts.
Figure 14: Methodologically, it doesn't make sense to compute a moving average of SPI or SPEI. I suggest using longer periods for compute the indices as a methodological correct solution.
Figure 15 and Table 6: Contain the same information; consider removing the figure.
Explain why a 12-month SPI and SPEI is used. I suggest considering shorter scales (1-6 months) as damages in Iberia are often related to these scales (Peña-Gallardo et al. 2019 NHESS, 19, 1215–1234).
Include units in the axes of the figures.
Citation: https://doi.org/10.5194/egusphere-2023-2177-RC3 -
AC1: 'Reply on RC3', Josep Barriendos, 02 Mar 2024
Answer:
The authors express their gratitude for the suggestions made in this review by Referee #3. In the following text, we provide a detailed answer to all those comments that have been suggested by Referee #3.
Comment:
The article analyzes droughts in the Mediterranean coast of the Iberian Peninsula during the period 1790-1830, utilizing pro-pluvia rogations and early instrumental data from Barcelona. While experiments combining documentary sources and long instrumental data are inherently interesting, this article, in its current form, lacks focus and is speculative, making it difficult to read. Additionally, the methods used are either unjustified or incorrect, and most of the conclusions are speculative, poorly supported by the results. The editing also lacks attention to detail, with figures lacking labels on axes, duplicate information in tables and figures, references that do not appear in the reference list (e.g., Morron 2020), and large parts of the text that are unnecessary or could be highly summarized for the paper's objectives
Answer:
We appreciate these general comments on the text.
The aspects commented on the text have been corrected. For example, the information is no longer repetitive between tables and figures and the style of the figures has also been edited to be clearer and more homogeneous between the different figures.
The references have been checked to ensure that they were all included in the bibliography and a reference that was misspelled has been rectified in the text, changing Moruno, 2020 for Moruno, 2021.
The remaining valuable comments on the methods used and the conclusions will be answered in detail and with justification in subsequent sections.
Comment:
I will begin my review by addressing the main problems with the proposed objectives. In the abstract, the principal objective is stated as follows: 'The objective of this study is to analyze the occurrence and magnitude of extreme droughts, lasting more than a year, in Spain during the Dalton Solar Minimum period (1790-1830).' However, this objective differs slightly from the main objective expressed in section 1.3: 'Analyze the patterns of drought episodes that affected the Spanish Mediterranean Basin during the Dalton Solar Minimum between 1790 and 1830 using instrumental and historical sources.'
Answer:
We are grateful for this clarification. The more generic reference to "Spain" has been changed from the abstract to "Spanish Mediterranean Basin". Thus, this slight difference has been eliminated by mentioning the same objective in the text (abstract and objectives). The data for the Spanish Atlantic Basin are considered to be used to support the detection and definition of the episodes.
Comment:
Several issues arise in achieving this objective. Firstly, it is necessary to clearly define the study area based on the data used. In the abstract, the study area is Spain, while in section 1.3, it is the Spanish Mediterranean Basin. Upon reading the paper, it becomes apparent that the correct area of study should be the North Spanish Mediterranean Basin, as most of the information and the most homogenous records are from this area.
Answer:
The reference to Spain in the abstract has been modified and the study area is now more coherent, using the expression "Spanish Mediterranean Basin" in all cases.
Regarding the change of the name of the study area to "North Spanish Mediterranean Basin", we appreciate the name suggestion. However, it has been considered among the authors that the original name better encompasses all the information analysed in the article, as it is not only the North Spanish Mediterranean Basin that is being studied. There is a significant amount of information within the "Spanish Mediterranean Basin" that corresponds to the central and southern sections. If the title were changed, as the reviewer suggests, it would not be understood why information from other Spanish territories is included and it would make it difficult to understand droughts as a social and historically interconnected phenomenon between different regions.
Comment:
Secondly, to achieve this objective it is mandatory to clearly define what is considered a drought episode, including its magnitude and duration (both for the instrumental and for the documentary period). This clarity is lacking in the methodology.
Answer:
We are grateful for this comment. We have added a detailed explanation of how we define drought episodes based on the documentary records of public administrative corporations that activate liturgical procedures such as pro pluvia rogations (see lines 339 to 347 of the revised manuscript).
Regarding the definition of the episodes from the instrumental data, this can be found next to the table of episodes in the results. A brief description of the criterion used in this paper to define drought episodes from precipitation data has been prepared. This text is found in the methodology section, within the subsection "2.3 Generation of drought indices" (see lines 396 to 401 of the revised manuscript).
Comment:
Regarding the 'additional objectives':
1. 'To qualitatively and quantitatively extend the AMARNA database on climate risks (Arxius Multidisciplinars per a l’Anàlisi del Risc Natural i Antròpic, from Catalan: Multidisciplinary Archives for the Analysis of Natural and Anthropogenic Risk) to incorporate droughts and different social processes linked to environmental impact in addition to hydrometeorological excesses (Tuset et al., 2022)': This objective stands out as one of the most significant contributions of the paper to the scientific community. It is crucial to provide a detailed description of the qualitative and quantitative improvements made to the AMARNA database. This includes specifics such as the number of new locations and dates of rogation ceremonies incorporated. Additionally, defining the Mediterranean locations covered by the database is essential for understanding the spatial pattern analysis attempted in the paper. The heterogeneity of available data may pose challenges to this analysis, so clarifying the extent and characteristics of the database is vital. It's also important to confirm if the database is publicly available and provide information on how it can be accessed, taking into account the data policy of NHESS (https://www.natural-hazards-and-earth-system-sciences.net/submission.html).
Answer:
The AMARNA database originally only provided data on water excesses recorded in historical periods for the Spanish Mediterranean Basins as a whole. Efforts are currently being made to add data on droughts to the AMARNA database. In this sense, the period from 1790 to 1830 has been a test to see how the recently obtained drought data and the existing water excess data fit together. Thus, the work proposed in this article involved going from 0 cases and episodes of drought for the Early 19th Century to the values with which the study was carried out.
Regarding online access to the AMARNA database: the situation with this project is that it is still under construction and therefore not yet available for public access. Only the period 1790-1830 has been completed, but it is still not publicly accessible because additional records are still being entered. The data used for the study period, however, can be shared upon request to the authors. In line with the NHESS data access policy, this detailed information is now included in the "Data availability" section of the revised manuscript.
In the case of the Early 19th Century, the different efforts to collect and organise the data on water excesses and droughts have resulted in a very characteristic spatial distribution of the data (Figure 1). Most of the points with information on water excesses collected in AMARNA are located in the Spanish Mediterranean basins. On the other hand, the information on droughts reaches points all over Spain, but with a higher density in the territory of Catalonia, between the CHE and the CIC (Figure 1). Some sentences explaining these considerations have been added (lines 489 to 499 of the revised manuscript).
Comment:
2. 'To compile and describe the variability of extreme hydrometeorological events (torrential rainfall and droughts) in the Spanish Mediterranean Basin during the DSM': The utility of analyzing torrential rainfalls alongside the main objective focused on drought events is not clear. If the authors believe it is necessary, they should provide a more detailed explanation of why it adds value to the analysis and how it contributes to the main objective, avoiding introducing unnecessary noise.
Answer:
A sentence has been added to the objectives clarifying the justification for analysing also the behaviour of torrential rainfall (see lines 324 to 326 in the revised manuscript). We understand that the Mediterranean climate has a marked irregularity. And the current situation, together with the modelled future, gives a greater interest in extending the knowledge of extreme situations of the past. Not only independently, but also by analysing these extremes (rainfall deficits and excesses) jointly to see how they interact with each other. In addition, spatio-temporally coherent periods of climatic anomalies have among their main characteristics in the study area, an increase in rainfall irregularity (Gil-Guirado et al., 2016).
The above justification has been included in the revised manuscript (see lines 326 to 328 in the revised manuscript).
This approach will also be applied in other work on the behaviour of extreme hydrometeorological extremes in other periods.
Comment:
3. 'To characterize the drought episodes, analyzed from historical data and the instrumental precipitation series of Barcelona, considering their duration, extension, and severity in high resolution for the period analyzed': This objective seems to overlap with the main one. Regardless, it is necessary to clearly define how duration, extension, and severity are computed both from rogation ceremonies and from SPI and SPEI.
Answer:
We appreciate the feedback. Indeed, additional objective 3 and the main objective are very similar. The main difference is that additional objective 3 takes into consideration the concepts of duration, extent and severity. For this reason, the objective has been rewritten to focus on the use of historical data. The above justification has been included in the revised manuscript (see lines 328 to 330 in the revised manuscript).
Comment:
4. 'To analyze the entire instrumental precipitation series of Barcelona spanning from X to Y in order to characterize periods of drought': I do not understand well the difference among this objective and the previous one. Whats mean 'X to Y??
Answer:
The reference to instrumental data in objective 3 has been deleted. Thus, objective 3 now focuses on historical data while objective 4 focuses on the Barcelona instrumental series. "From X to Y" is an expression used to mean from beginning to end. We have decided to change this expression so that the phrase is not so confusing. The above justification has been included in the revised manuscript (see lines 330 to 332 in the revised manuscript).
Comment:
Now I want to provide some comments order by the appearance in the text no by importance.
L. 43-58: The authors could discuss environmental droughts as a typology of drought, especially when considering their effects on the environment (L. 113).
Answer:
We understand the consideration of this concept of drought and its relevance as outlined by the reviewer. However, we can only consider drought on the basis of the criteria with which the documentary records we use were generated. In other words, we can mostly identify and classify episodes of drought according to their degree of rainfall or meteorological anomaly that affects the development of traditional rainfed crops (long-cycle cereals such as wheat or barley). Unfortunately, the administrative documentary sources in different historical periods in the Hispanic monarchy do not systematically follow the evolution of environmental aspects or the natural environment. For this reason, their introduction in a chronological series would have implied the consideration of inhomogeneous data. Therefore, their analysis has not been included in this article.
Comment:
L. 63-70: The explanation regarding pro pluvia rogations as a proxy for meteorological droughts is not entirely convincing. Previous studies have shown a clear link between rogations and agricultural processes, with seasonality tied to the agricultural calendar. I see the point of the authors about the daily resolution of the proxy, but I think that more evidences are required to affirm that rogation can be considered as a meteorological drought proxy. A comparison of precipitation in Barcelona and rogations at this location could shed light on this, and the authors should address the extrapolation of results to other climates more thoroughly.
Answer:
We appreciate these observations and have addressed this aspect and substantially improved it in the new text. That particular paragraph in the introduction on rogations has been deleted from the text. The information it contained was really confusing and not very explanatory of what the rogations are as a source of information. Moreover, it was a paragraph that did not fit well in that block of the introduction. The explanation of the rogations has now been strengthened in the methodology section in response to the issues raised in your commentary. The above justification has been included in the revised manuscript (see lines 379 to 386 in the revised manuscript). We hope that these changes respond to the reviewer's comment.
Comment:
L. 85-88: The statement that "the available knowledge focuses on very specific aspects during the instrumental period" is incorrect, and may be considered disrespectful to numerous authors who have worked on various aspects of droughts over the past decades. Citing studies like Van Loon & Van Lanen, 2012, does not support this assertion
Answer:
We are grateful for this suggestion. This sentence in its original form was incorrect and did not contribute to the content of the text. The sentence has been deleted to avoid this error.
Comment:
L. 184-197: The review of historical droughts in the Iberian Peninsula appears outdated, with the latest papers cited being from 2013. Given the significant advances in the field over the last decade, the authors should update this section with more recent references.
Answer:
More recent references on the subject have been introduced: Among others, Domínguez-Castro et al., 2021; Cuadrat et al., 2022; Garza-Merodio, 2017; Alberola & Arrioja, 2018; Ramírez-Vega, 2021; However, the authors would like to point out that the subject of historical droughts using documentary sources is still very limited in its development in the study area.
Comment:
L. 269-271: The use of two different stations to update the series of Barcelona until 2022 is mentioned, but the homogeneity of the final series is not analyzed. Since standardized drought indices are highly sensitive to inhomogeneities, it is crucial to analyze and address potential homogeneity issues in the updated series.
Answer:
This study focuses on the detection of severe precipitation anomalies. The homogenisation of the series would be part of an investigation with other objectives based on the same series.
We are aware that the available sections used to complete the Barcelona instrumental series come from points in the city with very different characteristics (from the coast to mountains at 500 m altitude). In our paper we focus on the anomalies within each of these series sections. Rainfall in the Mediterranean climate presents such a marked variability that obtaining a complete homogenised series is an objective and a later stage in this type of research.
In any case, the sections of data used in this study have been validated by the Meteorological Service of Catalonia, as they are official data. The above justification has been included in the revised manuscript (see lines 410 to 416 in the revised manuscript).
Comment:
L. 273-319: In this section, the authors need to provide a clearer explanation of how the AMARNA database has been “qualitatively and quantitatively” improved. It is unclear how many new data have been added to the database and how the information processing has been enhanced compared to previous papers. Additionally, instead of Table 3, it may be more beneficial for the authors to present a map showing the locations with information on extremes during the studied period and the length of this records. This really allows the reader to understand the studied area.
Answer:
An explanatory paragraph has been added on the type of data added to the AMARNA database for this study. Initially, the database only included water excesses and the contribution with the present manuscript is the introduction of information on water deficits. The above justification has been included in the revised manuscript (see lines 476 to 482 in the revised manuscript).
Table 3 has been modified so that it is accompanied by a map showing the various data points available for the study period (1790-1830) (see Figure 1 in the revised manuscript, lines 503-504). This map shows which points provide information on droughts and/or excess water. This allows us to see that, although the density of information for the Mediterranean basin is quite high, the spatial coverage of drought episodes is much more limited.
Comment:
L. 327-329: The authors seem unfamiliar with SPEI. Firstly the paper that describe the index is Vicente-Serrano et al. 2010 not Beguería et al. 2010 that describe a global database. The description of SPEI in the text is poor and lacks essential details as that the index try to replicate a balance of water in the atmosphere. The authors should specify how they computed atmospheric evaporative demand. Morover they must define and justify the temporal windows of the index and the threshold to consider drought conditions. These details significantly influence the results and should be thoroughly explained.
Answer:
We had not realised this serious error. We are very grateful for this observation. The reference has been modified, both in the text and in the bibliography.
A brief description of the index is given in the methodology section (see lines 518 to 523 in the revised manuscript). It is also not the intention of this text to provide an in-depth description of how the indexes work, but only a superficial description. It is not the aim of this publication to carry out a methodological reflection on their use.
We have considered that this type of index is already adequately explained in the scientific literature. For this reason, we have provided the corresponding references and have preferred to provide an overview of each of them, without carrying out a detailed analysis of each one. Instead, and bearing in mind the objectives of this work, we have focused our efforts on analysing the results generated by each of these indices. The contents are related to the objectives of this paper. However, as we pointed out at the beginning of this answer, in relation to SPEI we add the following clarification (see lines 523 to 529 in the revised manuscript): following Vicente-Serrano et al. 2010, in this work we calculate SPEI using monthly temperature and precipitation data. Potential Evapotranspiration (ETP) is calculated using the Thornthwaite (1948) method, which requires only monthly mean temperature. This method uses temperature to calculate a heat index and from this the ETP is determined. The difference between precipitation and ETP represents a simple water balance, and is fitted to a log-logistic distribution to standardise the SPEI over different time scales. This approach allows SPEI to incorporate the effects of temperature variability in the assessment of drought.
Comment:
L. 377: The term "relative normality" is unclear. The period 1806-1812 is noted as anomalous, due to the scarcity of ERE events, both below the mean. This period coincides with the Peninsular War (1818-1814), raising the possibility of factors affecting the availability of documentary sources or record-keeping during wartime. The authors could provide information on the continuity and homogeneity of the documentary sources analyzed during the studied period to shed light on the observed low density of events.
Answer:
The results section has been modified, both in the text and in the figures. In the case of the text where the term "relative normality" appears, it has been deleted and replaced by a clearer text (see lines 564 to 566 in the revised manuscript).
The documentary series consulted have the continuity and homogeneity that is usual in this type of sources. It is understandable that in a war scenario there could be very different types of incidents. However, there are two arguments in favour of homogeneity: firstly, despite the severity of the Napoleonic wars, they were of low intensity for the territory under study. In this case, it was generally a conflict in which the contenders hardly moved and took food resources from the same area. Secondly, the records collected correspond to local authorities, which implies that they are institutions not directly affected by the conflict. Their responsibilities are focused on the basic activities of their immediate territory, such as the development of crops and the collection of water resources for their citizens.
Finally, it can be explained that, in order to compensate for the possible effects on municipal documentation, private documentary sources (diaries and memoirs) appeared during the Napoleonic Wars, which can complement the official documentation.
Comment:
Figures 2, 3, 4, and 5 contain similar information. Suggest summarizing this information in one or two figures.
Answer:
Figures 2, 3, 4 and 5 have been deleted. The information contained in these figures is now shown in a single figure with two diagrams (see figure 2 of the revised manuscript).
Comment:
L. 386: “This anomaly may be due to the fact that in this basin no specific campaigns for compiling drought information have been carried out” It is necessary to define in all areas if he low number of ERE are due to lack of data. This is mandatory to understand figure 6.
Answer:
A paragraph has been introduced explaining this bias, which certainly occurs in the homogeneity of the data (See figure 1 of the revised manuscript). The main cause of this bias is that it has not been possible to work with all the points that we would have liked to due to the workload involved. This work exceeds the objectives of this manuscript, since, although there is an inherent bias in historical documentation, this fact is inherent to the discipline of historical climatology itself. On the other hand, the fact of having data from regions that have been studied in detail, as opposed to others that have been less studied but for which documentation is available, makes it possible to detect the spatial extent of the droughts. This is included among the objectives of the work.
In this sense, the Júcar basin (CHJ), specifically the departments of Valencia and Castellón, have this bias because the same systematic work has not been applied as in other regions for research on historical droughts. This is a research bias that also occurs in the Andalusian Mediterranean basins (CMA), the Guadiana basin (CGN) and the Miño basin in Galicia (NOR). On the other hand, the regions of Murcia (CHS), Alicante (CHS) and Catalonia (CIC and CHE) appear with a good representation of drought due to the campaigns carried out to obtain this information.
Figure 1 of the revised manuscript shows the number of data points that provide information on excess water for these regions.
Comment:
Figure 7: Define "case of drought." The abstract mentions droughts lasting more than a year, but this doesn't seem possible here.
Answer:
A complete description of drought cases has been introduced in the methodology section, in the same sense as detailed below:
Cases are the basic units of documentary record in which there is a mention of some kind of incidence of water deficit. They may be decisions by the authorities to initiate or continue pro-pluvia rogations, they may be qualitative records on rainfall within a drought episode, or records on the decision by the authorities to end the rogations once the drought is considered to be over.
Comment:
Figure 8: Explain how the "potential affected area" is computed.
Answer:
The interpolation and definition of the area potentially affected by drought has been obtained during the process of interpolation of the historical data for each of these episodes. This work has been carried out using Arc Map GIS software, using the Kernel Density tool. The explanation has been added in the footnote of figure 5 (See lines 641 to 646 of the revised manuscript).
The area obtained is logically a geographical abstraction of the territory in which the documented drought situation may be affecting the development of rainfed crops.
Comment:
L. 413: Clarify how the period 1812-1825 is possibly linked to Maldà Oscillation. Explain the nature of this link.
Answer:
The drought we are linking to the Maldà Oscillation is not that of 1812-1825, but an earlier episode from December 1797 to December 1799. The writing has been revised to avoid misunderstandings.
Comment:
L. 466: Show plots with the severity and duration of droughts.
Answer:
The indication pointed out by the reviewer was already available in the manuscript, but at the end of the whole process of analysing the results in that section. However, for the sake of clarity, we have replaced figure 16 attached to table 7 in the old version of the manuscript with a new figure 7 in the new revised version. In this way, and thanks to the reviewer's annotation, the duration and intensity of the different drought episodes analysed are shown more clearly. Likewise, it is now possible to appreciate those episodes whose intensity was higher than the average intensity and duration of all the episodes analysed. In this sense, the exceptional duration and intensity of episodes 6, 7 and 25 stand out.
Comment:
Figure 14: Methodologically, it doesn't make sense to compute a moving average of SPI or SPEI. I suggest using longer periods for compute the indices as a methodological correct solution.
Answer:
Figure 14 has been removed from the text. A panel has been created with the values of the three indices and no moving average is shown for these values (new Figure 6). We have decided to keep moving averages only for values extracted from historical documentation, as this is a procedure commonly used in historical climatology. But moving averages have been removed for drought indices. Indeed, the very computation of drought indices implies a certain effect of temporal aggregation when considering the values of long periods for their calculation.
Comment:
Figure 15 and Table 6: Contain the same information; consider removing the figure.
Answer:
The aim of this figure was to provide a summary and visual image of the discontinuities generated by the indices, following the chronological pattern used in the presentation of the indices themselves (1786-2022). However, the image certainly does not provide information that is not contained in the current table 5, so we have decided to remove it.
Comment:
Explain why a 12-month SPI and SPEI is used. I suggest considering shorter scales (1-6 months) as damages in Iberia are often related to these scales (Peña-Gallardo et al. 2019 NHESS, 19, 1215–1234).
Answer:
We have chosen 12-month indices because we are working with episodes that already have a significant severity. Choosing shorter periods of analysis would lead us to analyse droughts that are practically seasonal and that form a structural part of the climatology of this region, as shown by works such as that of Noguera et al. (2020). This line is followed by other recent scientific works (Mathbout et al., 2021). In addition, this work highlights that the use of various drought indices is especially valid for detecting the most intense drought episodes on a regional scale. We want to focus the study on those episodes of drought that have the most significant social, productive and economic impacts. This is a key point in the work. Some relevant studies, such as Espín-Sánchez and Gil-Guirado (2022), have shown that the socio-environmental systems in the study area presented adaptation and resilience strategies adapted to droughts of high intensity but short duration. However, when the drought lasted for several seasons, social, economic and political problems arose, which are detected in the historical documentation.
Comment:
Include units in the axes of the figures.
Answer:
Thank you for noticing this oversight. In the diagrams where applicable, the units or category names have already been added, as appropriate.
References of the answersEspín-Sánchez, J. A., & Gil-Guirado, S. (2022). Praying for rain, resilience, and social stability in Murcia (southeast Spain). Ecology and Society, 27(2).
Gil-Guirado, S., Espín-Sánchez, J. A., and Prieto, M.: Can we learn from the past? Four hundred years of changes in adaptation to floods and droughts. Measuring the vulnerability in two Hispanic cities, Climatic Change, 139, 183-200, https://doi.org/10.1007/s10584-016-1768-0, 2016
Mathbout, S., Lopez-Bustins, J. A., Royé, D., & Martin-Vide, J. (2021). Mediterranean-scale drought: Regional datasets for exceptional meteorological drought events during 1975–2019. Atmosphere, 12(8), 941.
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Citation: https://doi.org/10.5194/egusphere-2023-2177-AC1
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