the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 17 Mar 2025
Brief communication: Sharp winter precipitation transition on the southern edge of the Tibetan Plateau
Abstract. The Tibetan Plateau is a high-altitude arid region, where limited in-situ precipitation measurements are available. In this communication, we document a strong precipitation gradient at the southern edge of the Paiku Co catchment (southern Tibetan Plateau) from in-situ data and atmospheric model outputs. In particular, we use water pressure time series from proglacial lakes, two automatic weather stations, and data from ERA5-Land reanalysis and CORDEX-FPS-CPTP ensemble. We show that precipitation can vary by one order of magnitude over a short distance of 10 km in a rather smooth terrain throughout the winter and the pre-monsoon season. This large precipitation gradients marks the transition between the great Himalayas ans the Tibetan Plateau.
Competing interests: Emily Collier is a member of The Cryosphere editorial board.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.- Preprint
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RC1: 'Comment on egusphere-2025-863', Anonymous Referee #1, 08 Apr 2025
Overview
This paper presents in situ observed precipitation at three locations in the central Himalaya and compares these in situ precipitation measurements to two simulated estimates. One of the in situ measurement uses a novel technique where precipitation is derived from pressure measurements taken from a frozen lake. The results demonstrate a large gradient in the observed precipitation across a very small distance, and briefly discuss the ability of the simulated datasets to represent those gradients.
Generally it’s well known that large windward/leeside gradients can exist in regions where the precipitation is strongly modified by terrain, and I think this could be better referenced in this paper. However, the novelty here is in the use of the frozen-lake-measured precipitation and in particular its utility in such a data-sparse environment, and the test and figures are generally well presented. I have several specific comments below that would improve the paper that I recommend addressing before acceptance.
Specific comments
- Figure 1:
- It would be very helpful for the reader less familiar with the region to include a thumbnail/inset panel showing the broader location of this (fairly small) geographical location
- I initially didn’t understand why the three in situ markers on the colorbars of b and c shifted values between the panels, then I realized that (I think) these represent the model values at the three closest gridpoints to the in situ locations. This should be made more clear in the Figure caption, and a suggestion is to use outlined markers (diamond, square, and triangle for Yala, Golojang, and Paiku, respectively) rather than filled markers on panels b and c and the colorbars.
- I suggest you add the location of Paiku CO (which I believe is slightly off the northern end of the map) to these figures.
- 118-122 and L. 158-159: The discussion/comparison to Paiku Co values (which are not shown but referenced from Lei et al. 2021) is confusing, because Paiku Co is not shown on the paper’s map, and it’s unclear why the data from that site are not used in the analysis. If they are available, including the Paiku Co data would be a strong addition to the paper. If not available, this should be stated more explicitly, and any differences between the datasets (e.g., period of overlap, or methodological differences, etc) should be more clearly stated as well.
- 190-199: The text in this paragraph meanders and is a bit challenging to follow. I suggest dividing it into two paragraphs, one which describes the comparison of in situ to models and one which describes the potential differences between the AWS and PT methods (and the latter’s potential to miss smaller snowfall events)
- 209-210: While the larger gradients in CPTP may be promising, it’s difficult to know whether the even larger values in CPTP to the west and south of Yala AWS are realistic or overdone (while numerical models can accurately depict orographic precipitation, some studies have shown wet biases in high terrain, e.g., He et al. 2019) – perhaps some comment along these lines could be added.
- 218: These results are not shown and thus should, at a minimum, be stated as such. However, I would encourage adding these results, either as an additional figure, panel in an existing figure, or to Figure A1
- 222: I suggest citing figure A1 somewhere in this sentence
- 231-232: ‘However… magnitudes.’: I suggest rewriting this sentence somewhat for clarity, e.g., ‘It’s possible smaller events were not detected because of their small signal compared to large noise in the measurements.’
- 237: ‘despite it is located much closer to the lake.’ – please rewrite for clarity, e.g., ‘Golojang is closer to Paiku AWS than to Yala AWS’
- 243-244: lines 207-208 state (accurately, in my opinion) that no conclusions can be drawn regarding which dataset best-represents the in situ observations – I suggest this sentence be revised to better match that sentiment.
Errata
- 7: ‘gradients marks’ -> ‘gradient marks’. As written this phrase contains a subject-verb agreement error (gradients is plural, marks is singular) – several errors of this type appear in the paper, and hereafter I simply note them without description
- 217: ‘thirty year’ -> ‘thirty years’
- 218: ‘precipitation… reveal’ -> ‘precipitation … reveals’
- 232: ‘signals’->’signal’
References
He et al. (2019) Can Convection‐Permitting Modeling Provide Decent Precipitation for Offline High‐Resolution Snowpack Simulations Over Mountains? https://doi.org/10.1029/2019JD030823Citation: https://doi.org/10.5194/egusphere-2025-863-RC1 - AC1: 'Reply on RC1', Titouan Biget, 28 Aug 2025
- AC2: 'Reply on RC1', Titouan Biget, 28 Aug 2025
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RC2: 'Comment on egusphere-2025-863', Anonymous Referee #2, 25 May 2025
This manuscript proposes the use of vapor pressure over frozen lake surfaces to estimate cold-season snowfall, offering a practical approach to address the challenges posed by limited and difficult in-situ snowfall observations over lake areas. While the study presents certain merits and has reference value for related hydrometeorological research, several key issues must be addressed before it can be considered for publication.
1. The authors repeatedly highlight the use of “new observations.” However, both the methodological framework and the ground-based measurements employed are not novel in the field. The authors should clearly articulate what is truly innovative about their observational strategy or data application, and avoid overstating the originality.
2. The concept of “winter precipitation transition” is central to the manuscript, yet it lacks a clearly defined temporal scale. It remains unclear whether this refers to intra-annual seasonal transitions (e.g., winter to pre-monsoon) or to interannual variability in winter precipitation. This ambiguity persists in the title, abstract, and main text. The authors must explicitly clarify the temporal framework throughout the manuscript. Additionally, the pronounced increase in precipitation from winter to pre-monsoon is a well-recognized climatological feature in many regions, particularly across the southern Tibetan Plateau. Prior studies have documented a spring precipitation peak in this region. Therefore, the transition described in Golojiang is not a unique phenomenon and should be contextualized within broader regional precipitation dynamics.
3. The manuscript emphasizes that using lake surface vapor pressure can help identify snowfall events that may be missed by conventional precipitation measurements. However, the authors should also assess whether this method can reliably capture larger-scale precipitation events typically recorded by standard instruments. A more comprehensive evaluation of the method’s strengths and limitations is necessary to support the reliability and generalizability of the results.
The manuscript presents an interesting approach, but substantial revisions are required to clarify its novelty, conceptual framework, and methodological reliability. I encourage the authors to address the concerns raised above to enhance the scientific clarity and impact of the study.
Citation: https://doi.org/10.5194/egusphere-2025-863-RC2 - AC3: 'Reply on RC2', Titouan Biget, 28 Aug 2025
Data sets
Water pressure time series from Golojang Co Yanbin Lei, Fanny Brun, Tandong Yao, Walter Immerzeel, and Titouan Biget https://doi.org/10.5281/zenodo.14894696
Model code and software
Precipitation-computation-using-pressure-series-from-Tibetan-lake Titouan Biget https://doi.org/10.5281/zenodo.14894770
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