| 07 Jul 2026
Development and comparison of documentary-instrumental and circulation-based multi-centennial precipitation reconstructions for Dublin, Ireland
Abstract. This study develops a multi-centennial reconstruction of precipitation for the Greater Dublin Area, Ireland, using documentary, instrumental, circulation-based, and proxy evidence. Three independent reconstructions are produced for two contrasting water-resource domains, including: a monthly scaled version of the Jenkinson documentary-instrumental rainfall dataset for 1711–1977 produced by an earlier analysis for the island of Ireland; a circulation-informed monthly statistical ensemble based on Lasso and Random Forest models for 1748–1994; and an annual oak cellulose δ¹⁸O reconstruction of May–August precipitation extending to 1200 CE. Reconstructions were assessed against 1 km gridded rainfall observations for the common overlap period 1865–1977 using correlation, bias, error metrics, SPI-based event detection, and agreement in ranked wet and dry extremes. Long-term UK rainfall series and an extended Dublin snow and sleet series were used as independent comparators. Both the Jenkinson and statistical ensemble reconstructions reproduce observed monthly, seasonal, and annual rainfall variability, but the Jenkinson reconstruction shows the strongest agreement across most metrics and better captures wet and dry extremes. The statistical ensemble provides an independent, physically interpretable reconstruction, although it tends to smooth variability and under-represent event magnitude. The δ¹⁸O reconstruction shows weaker interannual agreement with observed May–August rainfall but provides a valuable longer-term perspective on summer hydroclimatic variability. Divergence between the Jenkinson and ensemble reconstructions before the mid-nineteenth century, particularly in winter and spring, is consistent with possible snow- and sleet-related undercatch in early precipitation sources which affects the Jenkinson reconstruction. Summer rainfall during the eighteenth century remains uncertain, with evidence for increased regional hydroclimatic heterogeneity. Together, these reconstructions provide a stronger basis for contextualising historical droughts and pluvials affecting Dublin and for stress-testing water-resource systems beyond the instrumental period.
Summary: The manuscript presents several reconstructions of monthly and seasonal precipitation in two regions close to Dublin, covering the past few centuries. The reconstructions are based on observational data sets from a gridded, station-based long record from the Irish Weather Service, documentary-observational data from two statistical models that take long records of circulation and temperature indices from the Western North Atlantic and Western Europe, and finally, a time series of Delta O18 that is linearly translated to seasonal (mostly summer) precipitation.
Recommendation: I have a very positive impression regarding the technical aspects of the manuscript, but I also have more critical suggestions regarding the target journal and the quality of the figures. Both critical remarks are related, and the way to address them depends on the objectives of the authors and the editor's opinion.
Main points
1) The statistical and data-handling aspects are very good, and I wish to congratulate the authors for the thorough statistical analysis and the methodological descriptions. They are very clear and comprehensive. I do not have suggestions for any improvement in this regard, other than the minor point that the physical units of RMSE and MAE are missing in all tables.
2) My critical comments are as follows: whereas the statistical and data aspects are flawless, the manuscript does not contain any discussion of physical drivers for rainfall variability or of possible imprint of volcanic eruptions or greenhouse gases (trends in the 20th century, sudden changes during the Krakatoa or Tambora eruptions?, Any connection to the Year of the Slaughter in Ireland 1739-1740 (Jones and Briffa, Climatic Change (2006) 79: 361–379? Any connection to the Central England temperature series? The study is silent about all these aspects, which leads me to my second critical comment.
3) Is Climate of the Past the correct target journal? Evaluating the present version of the manuscript, I would rather believe that it would be better hosted by ESSD, given that it is very data-centric and void of other climatological or dynamical elaborations. Depending on how this question is answered, the manuscript could go to ESSD with, in my opinion, rather minor revisions, or it may remain in Climate of the Past, but then a whole new section should be included, for example, focusing on the dynamical aspects that I mention in my point 2.
I do think that the reconstructions are very interesting, and they are definitely worth deeper exploration. I would welcome it if the authors wished to pursue the second path and expand the study. If not, however, I believe that the present version is a bit short of content for Climate of the Past. Alternatively, the authors may consider converting this manuscript to Part I of a two-part manuscript, with Part1 published in ESSD and Part 2 in Climate of the Past.
4) Related to the previous point is the issue of the quality of the figures. They are all of low resolution, which in principle should not be a terrible problem. In this case, however, it does become an issue. I have been trying to discern by eye whether one can see an impact of volcanic eruptions in the series, or whether rainfall anomalies can be related to previously published temperature reconstructions, but the low resolution does not allow me to really assess the timing of peaks in the time series. To be fair, the data have been made available, but an interested reader should be able to clearly see all details of the time series in the manuscript. As all plots include several time series, with different colours that are not well defined in the low-resolution figures either, this is not easy at all. The clear value of the reconstructions is somewhat diminished by the low figure resolution.
Minor points
5) Figure 1, please include geographical coordinates.
6) ‘We assess the consistency of the top 20 wettest and driest years between 1865 and 1977 across
each reconstruction and observations using the Jaccard Similarity Coefficient...’
This suggestion is more a matter of taste but it would help the reader to add that the JI is related to the more usual F1-score by JI=F1/(2-F1). Or is JI in this case based on three (plus,neutral,minus) categories?
7) Table 2 ,3 4,5 , include units of RMSE, MAE and PBIAS
8) All reconstructions seem to underestimate the observed variability. For instance, in the scatter plots shown in Figures 4 and 5, the range of the x-axis (observations) is always larger than the y-axis (reconstructions). This difference in range can be misleading. The text does discuss the underestimation of extremes, but I do suggest redrawing the scatter plots using the same range for both axes.
Related to this point, it seems to me, just by eyeballing, that these scatter plots indicate a non-linear link between observations and reconstructions. Even with the unequal axis ranges, it seems that the data cloud is ‘bent’ . This, of course, may be related to the underestimation of extremes, or perhaps a deeper issue throughout the whole range of the reconstructions.