the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 19 Sep 2023
Potential modulation of Indian Ocean basin mode on the interdecadal variations of summer precipitation over the East Asian monsoon boundary zone
Abstract. Based on long-term observational and reanalysis datasets from 1901 through 2014, this study investigates the characteristics and physical causes of the interdecadal variations in the summer precipitation over the East Asian monsoon boundary zone (EAMBZ). Observational evidence reveals that the EAMBZ precipitation featured prominent interdecadal fluctuations, e.g., with dry summers during the periods preceding 1927, 1968–1982, and 1998–2010, and wet summers during the periods of 1928–1938, 1946–1967, and 2011 onwards. Further analyses identify that the Indian Ocean basin mode (IOBM) is an important oceanic modulator responsible for the interdecadal variations of the EAMBZ precipitation. When the cold phase of the IOBM occurs, an anomalous cyclonic circulation is excited around the northeast corner of the tropical Indian Ocean, which further induces a “north-low–south-high” meridional seesaw pattern over the Northeast China–subtropical western Pacific (SWP) sector. Such seesaw pattern is conducive to the enhanced EAMBZ precipitation through linking favorable environments for the transportation of water vapor from the SWP and the convergence over EAMBZ at interdecadal timescales. For this reason, a physical-empirical model for the EAMBZ precipitation is developed in terms of the IOBM cooling, which can well capture its interdecadal fluctuations and reflect their steady relationship. The key physical pathway connecting the IOBM cooling with the interdecadal variations of the summer EAMBZ precipitation is supported by the numerical results based on the large ensemble experiment and the Indian Ocean pacemaker experiment. Our findings may provide new insights into the understanding of the causes of the interdecadal variations in the summer EAMBZ precipitation, which may favor the long-term policy decision making for the local hydrometeorological planning.
- Preprint
(2135 KB) - Metadata XML
-
Supplement
(712 KB) - BibTeX
- EndNote
Status: closed
-
RC1: 'Comment on egusphere-2023-1529', Anonymous Referee #1, 17 Oct 2023
This paper uses observations, re-analysis output and model simulations to examine interdecadal variability in the East Asian monsoon boundary zone, particularly in precipitation. The authors find that the cold phase of the Indian Ocean basin mode prompts anomalous cyclonic circulation over the north-eastern Indian Ocean, which ultimately enhances moisture transport from the Pacific Ocean to the boundary zone. I apologise to the authors for the delay in submitting this review.
I have a few a few comments about this paper, primarily about the presentation and discussion. I recommend major revisions.
This paper uses far too many acronyms: I counted 30 in total. While some are fine to keep – if they are mentioned more than five or so times – others are used sparingly. Unfortunately, this makes large sections of the paper very difficult to follow: I spent a great deal of time trying to remember what each acronym was, or flicking backwards to look it up again. Consequently, I found the science message was often unclear. (And as something of an aside, a couple of acronyms were poorly chosen: EU commonly means European Union, and P-E could be confused with “precipitation minus evaporation”, particularly to an audience of atmospheric scientists.)
The coastlines plotted on the figures are very faint: it is difficult to pick out the important features when it’s unclear where they are. Also, axes and colour bars should be labelled on the figures as well as in the captions. And in Figure 6, hatching is used to indicate significance, whereas in other figures the authors use dots: please use just one for consistency.
I think the authors need to include more details about the model simulations described in Section 2.6 They subtract one set of simulations from the other, but it is not clear to me how this achieves the authors’ stated goal (line 205). Please. Explain make clear how the two sets of simulations are different: why is internal variability arising from Indian Ocean SSTs unique to one simulation and not the other? And indeed – and I apologise if I have missed something – it is unclear how these models are used subsequently. I think it would be helpful to note, as the results are discussed, which data sets are being used at each point.
The physical-based empirical model (Section 3.4) appears to be behind a key result of the paper: it is mentioned in the abstract. But this section feels rather brief. Could the authors perhaps discuss the implications of their model a bit further? They say it captures some of the observed interdecadal variability: what about its shortcomings? How is this result helpful?
And related to the above point, I think the discussion (Section 4) could be improved. At present, it summarises the results – which are they summarised again in the Conclusion – but gives little sense of how the results fit into existing knowledge. How does this work move the field forward? What questions arise from it?
Citation: https://doi.org/10.5194/egusphere-2023-1529-RC1 - AC1: 'Reply on RC1', Jing Wang, 12 Dec 2023
-
RC2: 'Comment on egusphere-2023-1529', Anonymous Referee #2, 13 Nov 2023
Review of “Potential modulation of Indian Ocean basin mode on the interdecadal variations of summer precipitation over the East Asian monsoon boundary zone” by Jing Wang et al.
This study looks into the link between the Indian Ocean Basin mode (IOBM) and the summer precipitation over the East Asian monsoon boundary zone (EAMBZ). The authors discusses, during cold phase of IOBM, the EAMBZ has enhanced precipitation. This is through the formation of an anomalous cycolonic circulation in the North-East corner of tropical Indian Ocean driving a North-low-South-high pattern taking place in the interdecadal timescales.
Overall, this study attempts to understand the features of precipitation over EAMBZ on interdecadal timescales. I would recommend this study for major revision and has to address below queries:
Major comments:
- The title is not clear. It seems to not highlight that this study investigates how modulation of IOBM causes a a change in precipitation in the EAMBZ on interdecadal timescales. The title could be changed to “Modulation of Indian Ocean basin mode potentially drives the interdecadal variations of summer precipitation over the East Asian monsoon boundary zone”. The authors ought to think on this and clarify.
- The study primarily provides mechanistic explanation on the link between IOBM and precipitation over EAMBZ during the cold phase only. The authors need to provide and discuss the processes during the IOBM warm phase and corresponding precipitation over EAMBZ, or is it that the authors discuss this somewhere and I have missed it.
- I would urge the authors to make clear discussion on past studies (it is there already but somehow the present structure mingles them) which investigates the interannual variations of precipitation over EAMBZ. I recommend the literature review made in the “Introduction" to be more structured. Right now it reads unclear and less motivating to read through. Section 2 in the manuscript for instance, is very well structured and written. Another concern, far too many acronyms are used.
- IN addition, as the authors have discussed several processes that are interlinked and connects the IOBM and EAMBZ precipitation. It is necessary that they provide a schematic and/or flowchart showing the interlinkages and processes. This is would be very helpful for the readers .
Minor Comments:
Figure 1- Improve the resolution. It is a key figure.
P2L82-83: I would urge the authors to be elaborate here.
P6L241: I also find dry summers around 1940. Authors mention about Si et al. 2021 here. Please write the context, since that paper looks into Northeast Asian summer monsoon and AMO.
P8L320: “localised atmospheric responses” Please explain.
Equation5: The P-E model, please discuss the possible inabilities of this model. Also, is this model developed for this study (as mentioned in abstract) or does it follows from past studies such as Jeong et al. 2021. Please make this clear.
Citation: https://doi.org/10.5194/egusphere-2023-1529-RC2 - AC2: 'Reply on RC2', Jing Wang, 12 Dec 2023
Status: closed
-
RC1: 'Comment on egusphere-2023-1529', Anonymous Referee #1, 17 Oct 2023
This paper uses observations, re-analysis output and model simulations to examine interdecadal variability in the East Asian monsoon boundary zone, particularly in precipitation. The authors find that the cold phase of the Indian Ocean basin mode prompts anomalous cyclonic circulation over the north-eastern Indian Ocean, which ultimately enhances moisture transport from the Pacific Ocean to the boundary zone. I apologise to the authors for the delay in submitting this review.
I have a few a few comments about this paper, primarily about the presentation and discussion. I recommend major revisions.
This paper uses far too many acronyms: I counted 30 in total. While some are fine to keep – if they are mentioned more than five or so times – others are used sparingly. Unfortunately, this makes large sections of the paper very difficult to follow: I spent a great deal of time trying to remember what each acronym was, or flicking backwards to look it up again. Consequently, I found the science message was often unclear. (And as something of an aside, a couple of acronyms were poorly chosen: EU commonly means European Union, and P-E could be confused with “precipitation minus evaporation”, particularly to an audience of atmospheric scientists.)
The coastlines plotted on the figures are very faint: it is difficult to pick out the important features when it’s unclear where they are. Also, axes and colour bars should be labelled on the figures as well as in the captions. And in Figure 6, hatching is used to indicate significance, whereas in other figures the authors use dots: please use just one for consistency.
I think the authors need to include more details about the model simulations described in Section 2.6 They subtract one set of simulations from the other, but it is not clear to me how this achieves the authors’ stated goal (line 205). Please. Explain make clear how the two sets of simulations are different: why is internal variability arising from Indian Ocean SSTs unique to one simulation and not the other? And indeed – and I apologise if I have missed something – it is unclear how these models are used subsequently. I think it would be helpful to note, as the results are discussed, which data sets are being used at each point.
The physical-based empirical model (Section 3.4) appears to be behind a key result of the paper: it is mentioned in the abstract. But this section feels rather brief. Could the authors perhaps discuss the implications of their model a bit further? They say it captures some of the observed interdecadal variability: what about its shortcomings? How is this result helpful?
And related to the above point, I think the discussion (Section 4) could be improved. At present, it summarises the results – which are they summarised again in the Conclusion – but gives little sense of how the results fit into existing knowledge. How does this work move the field forward? What questions arise from it?
Citation: https://doi.org/10.5194/egusphere-2023-1529-RC1 - AC1: 'Reply on RC1', Jing Wang, 12 Dec 2023
-
RC2: 'Comment on egusphere-2023-1529', Anonymous Referee #2, 13 Nov 2023
Review of “Potential modulation of Indian Ocean basin mode on the interdecadal variations of summer precipitation over the East Asian monsoon boundary zone” by Jing Wang et al.
This study looks into the link between the Indian Ocean Basin mode (IOBM) and the summer precipitation over the East Asian monsoon boundary zone (EAMBZ). The authors discusses, during cold phase of IOBM, the EAMBZ has enhanced precipitation. This is through the formation of an anomalous cycolonic circulation in the North-East corner of tropical Indian Ocean driving a North-low-South-high pattern taking place in the interdecadal timescales.
Overall, this study attempts to understand the features of precipitation over EAMBZ on interdecadal timescales. I would recommend this study for major revision and has to address below queries:
Major comments:
- The title is not clear. It seems to not highlight that this study investigates how modulation of IOBM causes a a change in precipitation in the EAMBZ on interdecadal timescales. The title could be changed to “Modulation of Indian Ocean basin mode potentially drives the interdecadal variations of summer precipitation over the East Asian monsoon boundary zone”. The authors ought to think on this and clarify.
- The study primarily provides mechanistic explanation on the link between IOBM and precipitation over EAMBZ during the cold phase only. The authors need to provide and discuss the processes during the IOBM warm phase and corresponding precipitation over EAMBZ, or is it that the authors discuss this somewhere and I have missed it.
- I would urge the authors to make clear discussion on past studies (it is there already but somehow the present structure mingles them) which investigates the interannual variations of precipitation over EAMBZ. I recommend the literature review made in the “Introduction" to be more structured. Right now it reads unclear and less motivating to read through. Section 2 in the manuscript for instance, is very well structured and written. Another concern, far too many acronyms are used.
- IN addition, as the authors have discussed several processes that are interlinked and connects the IOBM and EAMBZ precipitation. It is necessary that they provide a schematic and/or flowchart showing the interlinkages and processes. This is would be very helpful for the readers .
Minor Comments:
Figure 1- Improve the resolution. It is a key figure.
P2L82-83: I would urge the authors to be elaborate here.
P6L241: I also find dry summers around 1940. Authors mention about Si et al. 2021 here. Please write the context, since that paper looks into Northeast Asian summer monsoon and AMO.
P8L320: “localised atmospheric responses” Please explain.
Equation5: The P-E model, please discuss the possible inabilities of this model. Also, is this model developed for this study (as mentioned in abstract) or does it follows from past studies such as Jeong et al. 2021. Please make this clear.
Citation: https://doi.org/10.5194/egusphere-2023-1529-RC2 - AC2: 'Reply on RC2', Jing Wang, 12 Dec 2023
Viewed
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 279 | 71 | 26 | 376 | 35 | 17 | 15 |
- HTML: 279
- PDF: 71
- XML: 26
- Total: 376
- Supplement: 35
- BibTeX: 17
- EndNote: 15
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1