Using GRACE Data to Study the Impact of Snow and Rainfall on Terrestrial Water Storage in Northeast China

Round 1

Reviewer 1 Report

Dear Authors,

I have read the manuscript entitled "Using GRACE Data to Study the Impact of Snow and Rainfall on Terrestrial Water Storage in Northeast China". Overall, the aims and scope seem interesting, and the manuscript should be published. On the other hand, some parts need clarifying. Moreover, I'm not too fond of the part dealing with the simulation of precipitation contribution back to the year 1981. All in all, we can predict (or extrapolated) signals with sufficient uncertainty only in intervals close to measured data. Please either omit this part in your manuscript or provide a numerical experiment based on real data, showing that such simulation works. Thus My personal feeling is that the manuscript should be accepted after major corrections. All my comments are provided below. 

Detail comments: l – line, p – page

p. 1, l. 25: Please explain what does ENSO mean.

p. 1, l. 40-43: Please be more specific here. The spatial resolution of GRACE models is about 200x200 km, so I can't entirely agree that terrestrial hydrological stations are limited by spatial distribution and poor data quality. Discuss here the quality of data from terrestrial stations and their spatial distribution and quality (uncertainty) of GRACE models.

p. 2, l. 45-57: Here, you omitted studies about the determination of ellipsoidal surface mass change from GRACE

Ditmar P (2018) Conversion of time-varying Stokes coefficients into mass anomalies at the Earth’s surface considering the Earth’s oblateness. J Geodesy 92(12):1401–1412.

Ghobadi-Far K, Šprlák M, Han S-C (2019) Determination of Ellipsoidal Surface Mass Change from GRACE Time-Variable Gravity Data. Geophysical Journal International, 219(1), pp. 248-259

And current studies:

Tangdamrongsub N, Han S-C, Jasinski MF, Šprlák M (2019) Quantifying Water Storage Change and Land Subsidence Induced by Reservoir Impoundment Using GRACE, Landsat, and GPS Data. Remote Sensing of Environment, 233, 111385

Yin W, Li T, Zheng W, Hu L, Han S-C, Tangdamrongsub N, Šprlák M, Huang Z (2020) Improving Regional Groundwater Storage Estimates from GRACE and Global Hydrological Models over Tasmania, Australia. Hydrogeology Journal, 28(5), pp. 1809-1825,

Please refer to these studies as well.

p. 2, l. 51-52: Spatial resolution of GRACE is 200x200 km; it could not monitor changes at regional or basin scales. Please correct it.

p. 3 and p. 4: I read this part three-times, but I do not understand. Please rewrite it-correct English. Reference to Formula 1 and GRACE Technical Note 13 is missing. Line 96-97 Why 2005-2010 here? In the abstract, it is 2004-2016. I do not understand Chapters 2.2 and 2.3 at all.     

p. 4, Formula 2: I missed terms related to sin function.

p. 4, l. 148: Is a sliding average a moving average?

p. 5, Fig. 2: Here, I am confused. You used a moving average with a length of 12 months. So I would expect that the first 6 and last 6 months disappeared. Please explain how it is?

p. 6, l. 171: greater or higher?

p. 6, Fig. 4: spectral decomposition results or periodogram?

p. 6, Table 1: How did you estimate the uncertainty of annual amplitude. I did not find it in the text of the manuscript.  

Author Response

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Reviewer 2 Report

1) In figure 6 the SWE and snowfall as well as snow depth show much different spatial patterns. Why is this? The authors mention something about the impact of temperature on snowmelt but can this explain these differences in all months from December to March?

2) The equations of RMSE and ME are widely known and do not offer anything to the manuscript. A simple bibliographic reference in the text for them would be enough.

3) In the discussion section the main findings of the study should be compared with similar efforts from the international literature. For example, have other researchers who followed the same methodologies and approaches concluded similar results? Are there many successful cases that Grace data were used to estimate snow and rainfall components of TWS? There are some comparisons in the manuscript with few studies from the international literature but more relevant bibliographic references and depth in the discussion is needed.  

Author Response

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Reviewer 3 Report

The authors analyze the influence of rainfall and snowfall on variations in terrestrial water storage (TWS) in Northeast China from GRACE (Gravity Recovery and Climate Experiment), GlobSnow snow water equivalent product, and ERA5-land monthly precipitation, snowfall and snow depth data. They found that data from GRACE satellite mission are useful for monitoring large areas of stable seasonal snow cover and variations in TWS in Northeast China at both seasonal and interannual scales. They also found that annual fluctuations of TWS and rainfall in Northeast China appear to be influenced by ENSO events with a lag of 2–3 years.

From the reviewer point of view the article is well structured, organized and written.

However, major comment is concerning the spectral inconsistency between data being analyzed. The authors used GRACE-based Global Geopotential models (GGMs) truncated at degree and order (d/o) 60 that corresponds to the spatial resolution of 3 arc-degree, while other data such as GlobSnow Snow “after filtering” of 1 arc-degree, ERA5-land data is 0.1 arc-degree . Moreover, the authors used DDK4 filter which reduce the spatial resolution of GRACE-based GGMs to d/o 40-50. Based on this all inter-comparisons results obtained will be artifacts. The reviewer recommend the authors to make all the data used consistent in terms of spatial resolutions, and then, conduct the inter-comparison between the data.

 

Some detailed corrections:

1. All abbreviations should be defined. For example in line 45, the abbreviation “GRACE” should be defined.
2. Line 142, motivation of using Eq. 2 should be given and a proper reference for Eq. 2 should be provided.
3. Line 147, analysis of Figs 2 and 3should be added.
4. Line 147, “TP data” should be defined.
5. Line 148, motivation for why the authors select “sliding average method” in particular should be provided.
6. Line 152, “Formula” should be “formula”.
7. In Table 1, Annual amplitude sigma, Annual phase and Annual phase sigma should be analyzed in the context of article.
8. Lines 261-262, the repeated sentence “the maximum correlation coefficient between TWSA and SOI in Northeast China is 0.66,” should be deleted.
9. Line 268, the reference “Lu Aigang et al.” is written improperly.
10. Line 272, “water TWS” should be “TWS”.
11. Line 282, “As mentioned above” should be “As mentioned in section X”.

Author Response

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Round 2

Reviewer 1 Report

Dear Authors,

 

All my comments have been considered/explained. I recommend your manuscript for publication.   

 

Author Response

Thanks for your work and comments. We appreciate for your constructive comments.

Reviewer 3 Report

The reviewer has read the manuscript entitled “Using GRACE Data to Study the Impact of Snow and Rainfall on Terrestrial Water Storage in Northeast China”.

The authors have significantly improved the aforementioned manuscript.

There are some comments that should be considered before the publication of it.

• Through the manuscript, the suitability of references cited need to be checked out. For instance, line 39 “… terrestrial hydrological models [6]”, in the reviewer opinion, reference [6] seems unsuitable.
• Line 58, the term “ellipsoidal surface mass change” seems confusing, the authors should use more clear terminology.
• Line 69, “the middle and low latitudes” should be specified.

Author Response

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Author Response File: Author Response.docx