How much snow falls on the Antarctic ice sheet?

Palerme, C.; Kay, J. E.; Genthon, C.; L'Ecuyer, T.; Wood, N. B.; Claud, C.

doi:https://doi.org/10.5194/tc-8-1577-2014

Articles | Volume 8, issue 4

https://doi.org/10.5194/tc-8-1577-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/tc-8-1577-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 8, issue 4

Research article

|

22 Aug 2014

Research article |

| 22 Aug 2014

How much snow falls on the Antarctic ice sheet?

C. Palerme, J. E. Kay, C. Genthon, T. L'Ecuyer, N. B. Wood, and C. Claud

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Final revised paper (published on 22 Aug 2014)
Supplement to the final revised paper
Preprint (discussion started on 24 Feb 2014)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC C288: 'Review comments in plain text (see Supplement for formatted version)', Anonymous Referee #1, 24 Mar 2014
- AC C794: 'Response to Referee #1', Cyril Palerme, 28 May 2014
RC C566: 'Review of "How much snow falls on the Antarctic ice sheet?" by C. Palerme et al.', Anonymous Referee #2, 30 Apr 2014
- AC C802: 'Response to Referee #2', Cyril Palerme, 28 May 2014

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Cyril Palerme on behalf of the Authors (28 May 2014) Author's response Manuscript

ED: Referee Nomination & Report Request started (04 Jun 2014) by Michiel van den Broeke

RR by Anonymous Referee #1 (15 Jun 2014)

Suggestions for revision or reasons for rejection

Please see the formatted comments. In plain text:

Comments on the revised version of “How Much Snow Falls on the Antarctic Ice Sheet?”
Authors: C. Palerme, J.E. Kay, C. Genthon, T. L’Ecuyer, N.B. Wood, C. Claud
MS No.: tc-2014-22

General Comments
I am pleased to see an improved manuscript in most respects, although several old items in my review require additional comment. I suggest to the editor that the first two are disagreements that he must address. The English is good – a few grammatical issues are noted.

Specific Comments
1. Old item 1: Title: Authors – I continue to be confident that your scientifically-careful estimate over part of Antarctica can form a solid basis for estimating the total over all of Antarctica as an additional and valuable addition to the manuscript’s current results. You are in the best position to make this calculation, and the non-specialist community is not. Furthermore, my experience says that, absent this whole-continent estimate, the partial-continent estimate will be mis-used by the non-specialist community as representing all of Antarctica. Editor – At this juncture the authors and I disagree on this point, so you get to make a judgment call; I am asking for one additional, approximate, and reasonably estimated calculation that will answer the title’s question.
2. Old item 2: What does CloudSat miss? Despite the reply that very light precipitation and deposition are treated equally, I think the text tends to mention deposition more prominently and often than light precipitation.
3. Old item 3: “flags”: Authors – I repeat: the terminology of “flags” usually seems to be what we would call “overpasses” or “samples”. Indeed, each sample has flag values indicating liquid or solid. At a minimum, you have to be really clear about what “flag” means if you intend it to indicate “sample”. Editor – Another point of disagreement. I find this usage confusing; again, you get to make a judgment call.
4. Old item 6: P.1284,L.10 (old location): “Interpolation” is fine, but what kind? Nearest neighbor, bilinear, splined, …?

Technical Corrections
5. Old item 19: P.1282,L.3: Sorry for being unclear. I was suggesting saying “cloud particles and hydrometeors” because cloud was the point of CloudSat, and it’s important to remind the reader in these introductory remarks that the radar sees both.
6. L.4 “but is not yet available. Satellite observations …”
7. L.22-23: The 25% over a century and the 1.6 mm/year seem not comparable. If you mean 160 mm/century, I think it would be preferable to use the same units.
8. L.26: “… differs widely, ranging from”
9. L.27: CMIP3 is pretty out of date at this point. Is CMIP5 similar?
10. L.35-36: “… is therefore a need … precipitation observationally to …”
11. L.116: “occurrence”
12. L.136: “… 2011) among reanalyses. However, …” or do you mean “of any analysis”?
13. L.190-191: It might be helpful to point out that the standard error decreases as the square root, or at least “non-linearly”.
14. L.205: “… d’Urville than other sites where no”
15. L.213: Presumably the Barnston citation should come after the HSS, not where it is, which implies that Barnston found this CloudSat result.
16. L.231: “than” should be “as”.

Referee Report: PDF

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RR by Anonymous Referee #2 (24 Jun 2014)

Suggestions for revision or reasons for rejection

The authors have correctly addressed my initial concerns and I found the manuscript much improved compared to the previous version. There is only one issue (the main reason for the differences between CloudSat and ERA-Interim in the Antarctic interior) where I am not absolutely convinced by the authors' response. I take the opportunity of this second review to further lay out my argument (see below). However, this remains a minor concern overall and it should by no means prevent publication of the manuscript. At this stage, I only have minor comments (mostly of editorial nature) and therefore recommend the manuscript for publication subject to minor revisions. A number of these comments should be regarded as mere suggestions that the authors can decide to follow or not.

Line 4. Suggestion: "spaceborne" is already implied by "satellite". Either one could be removed.

Line 6. Suggestion: "produce" or "generate" would fit better here than "build".

Line 14. Suggestion: "does not use" instead of "did not use".

Line 18. In Antarctica, the transition of water to the gas phase occurs almost exclusively through sublimation rather than through evaporation. Therefore, consider replacing "evaporation" with "sublimation or "sublimation/evaporation". The same goes for line 281.

Line 33. Correction: "reanalyses" instead of "reanalysis".

Line 39. To avoid any confusion in the reader's mind, I would make it clear here that the focus of the paper will be on one of the term (the dominant positive contributor) responsible for the surface accumulation. I have read the Introduction several times, and each time I thought that this clarification would be helpful given that in a number of studies (especially modeling studies), precipitation is considered a first-order equivalent of surface accumulation.

Line 43. Suggestion: "the instrumentation is not always able to detect" instead of "must be able to detect".

Line 48. Suggestion: "potentially significant" instead of "considerable". Clear-sky precipitation is not very well quantified in Antarctica and its contribution to the total annual surface accumulation can vary substantially from year to year.

Line 58. Suggestion: "a good agreement". Delete "a".

Line 59. In Boening et al. (2012), the agreement is with regard to Antarctic precipitation "variability", not "measurements".

Line 75. Suggestion: "operational weather analyses" or "operational analyses"

Line 89. Suggestion: "estimates of uncertainties" instead of "estimated uncertainties"

Line 97. Suggestion: "Multi-year averaging" instead of "climatological averaging".

Line 103. Consider adding a brief note here mentioning the fact that the 5-day sampling of CloudSat products does not seem to be a concern for their ability to capture the climatology of precipitation, along with something like "(see Fig. 5 discussed below)".

Line 125. Delete ", which was", otherwise the sentence suggests that no other global reanalysis has been produced since ERA-Interim, which is incorrect.

Line 126. ECMWF is already defined at line 75.

Line 132. Precipitation is a product of ERA-Interim forecasts, not of its analysis. Consider rephrasing "precipitation is modified in the analysis" to something like "precipitation is influenced by the four-dimensional assimilation..."

Line 135. Bromwich et al. demonstrated the realism of ERA-Interim precipitation *variability*.

Line 152. "and where". Delete "and".

Line 171-172. "contribute for 4.10% and rain for 1.32%". I would delete "for".

Line 202. Suggestion: "Surface observations" instead "field observations".

Line 204. Same argument as the one above about ERA-Interim precipitation. Consider rephrasing the sentence to something like: "Humidity profiles obtained by radiosoundings influence the forecasts used to predict precipitation in ERA-Interim".

Line 209-210. The sentence beginning with "This threshold" only makes sense if it also gives CloudSat precipitation frequency at DDU (which based on Fig. 2 should be lower than 60%).

Line 213. Since the comparison of CloudSat versus ERA-Interim relies in part upon the Heidke skill score (mentioned at lines 213 and 224), it would make more sense to define it here (or at line 207) rather than later (currently at line 237).

Line 231. "than" instead of "as".

Line 246. There are no observations of cloudiness assimilated in ERA-Interim.

Line 250-251. The issue of the lesser agreement between CloudSat and ERA-Interim in the Antarctic interior is a point I already raised in my first review and about which I do not fully agree with the authors. They provide at lines 224-231 one argument (in my opinion, a very good one) as to why one should expect less agreement between CloudSat and ERA-Interim in the interior than on the coast. To further support this "threshold argument" (as opposed to the "data assimilation argument"), I would like to point out that there is very good agreement between CloudSat and ERA-Interim in West Antarctica (see Figs 4c and 4d), which happens to be a region where there is very little data assimilation, and certainly no radiosoundings. My suggestion would be therefore to present the "data assimilation argument" as a secondary explanation. However, I will not object if the authors decide not to do so.

Lines 307-308. Consider rewording the sentence beginning with "For instance". I assume here that the authors mean that the three locations with the largest ratios are isolated and not representative of other surrounding observations?

Line 310. A number of papers have investigated the climatology of Antarctic precipitation, mostly based on model data. Therefore, climatologies of Antarctic precipitation "have already been established". What the first sentence refers to is more precisely a climatology that 1) is based on observations rather than models, and 2) covers the whole continent (or at least a substantial portion of it).

Line 315. Suggestion: "The observed surface accumulation" instead of "the surface accumulation".

Line 320. Suggestion: "snowfall rates ... have"

Line 330. Suggestion: "mistaken for" instead of "confounded with".

Line 347. The connector "but" implies that EarthCARE will be able to provide data during the night. But the sentence doesn't say it.

References: Please correct all DOIs (none of them provide the correct information).

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ED: Publish subject to minor revisions (Editor review) (02 Jul 2014) by Michiel van den Broeke

AR by Cyril Palerme on behalf of the Authors (03 Jul 2014) Author's response

ED: Publish as is (16 Jul 2014) by Michiel van den Broeke

AR by Cyril Palerme on behalf of the Authors (16 Jul 2014) Manuscript