Mapping the Daily Rainfall over an Ungauged Tropical Micro-Watershed: A Downscaling Algorithm Using GPM Data

Round 1

Reviewer 1 Report

This manuscript presents an approach for downscaling satellite-derived GPM rainfall estimates in tropical watersheds. The approach uses (light modifications to) the traditional Mass-Dempsey mesoscale orographic model on the 1 arc second SRTM DEM. Vertical wind velocity is first computed, as induced by both slope and surface wind convergence. This is then used to calculate the hourly condensation rate, which is then translated into a diurnal rainfall estimate. The results are compared against data from 8 rain gauges, with reasonable results.

Overall, I found the manuscript to be interesting and the approach to be sensible (so far as I understood it). Obviously downscaling of satellite rainfall data is a valuable thing to do, especially in locations with sparse or unreliable field data. The results are generally impressive and seem to work at least as well as the raw data.

However, significant English issues made this manuscript difficult to read. These issues were sufficiently challenging to render some of the technical points of the methodology unclear (at least to me). Ultimately I do think the manuscript should be published, but I strongly suggest this manuscript undergo professional English language proofreading before an additional round of review.

Incomplete line-specific comments:

Title & throughout manuscript: Is “hydrological data conflict situation (HDCS)” a commonly used term? To me, the description on lines 52-54 of “ungauged, sparse rain gauges, missing rain gauge data, inefficient data sharing policies, or ineffective data management” don’t sound like something that would not be well-described as a “data conflict”.

Table 1. What is the datum/coordinate system used for the station locations? Are these lat/lon coordinates in WGS-84? Or something else?

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

• The abstract should be a total of about 200 words maximum. So, It should be shortened with core findings in this study.
• The conclusion is too simplified. The reviewer recommends that authors need to reinforce the content further by referring to the abstract.
• The resolution of the figure provided in the manuscript is too low. Please provide it again because I cannot check the contents.   
• I found many typos throughout the paper. For more details, please refer to the attachment.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

I have two major concerns which make me not able to give a high evaluation at this moment, I would recommend its resubmission after huge modifcations.

(1) Regarding the methodology, it calculates the meteorological winds using surface station observations (interpolation), and derive the vertical velocity using the winds with spatial resultion of 0.02 degrees. Personally, considering the high spatio-temporal variation of winds, I do not think these methods are reliable. Particularly, the vertical convection could happen at very small region scales, for example, a regional scale of 400-600 m in horizontal space which is much smaller than 0.02 degree (2 km), making the calculation of vertical winds highly unreliable for local convection.

(2) There are many writing issues that need correct before further reviewing. 

Regarding the first point, I have explained why I do not agree the method they used for winds. For the second point, there are too many writing issues, for example, for just the abstract Lines between 15 and 25: Line 15, ha should be hPa Line 15, "one that facing hydrological data conflict situation" has grammar error. Line 18, approach should be approaches; was should be were; Line 20, condition should be conditions Line 22-23, this sentence is not right with "Using ... could be used as ..." Line 25, "are" should be "is" Based on these two points, I would recommend resubmission after significant modifications. In principle, it is painy for me to read through the paper for several times due to the writing issues. Personally, I would like to do a further review after a singificant change of the writing issues.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

After reading the revised manuscript, my previous review stands. Overall, I the content of the manuscript is interesting and the approach appears to be sensible – so far as I understand it. But significant English issues still make this manuscript difficult to read, and are still sufficiently challenging to render some of the technical points of the methodology unclear (at least to me). I realize that the authors have made an attempt to improve these, but much more work remains to be done. Ultimately I do think the manuscript should be published, but I strongly suggest this manuscript undergo professional English language proofreading before an additional round of review. I do not think this is likely to occur on the time frame of a revision, so at this point I suggest the manuscript be rejected and resubmitted.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have revised their paper on my first review comments, but still the resolution of the figures has not been improved.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Mahmud et al. “mapping the daily rainfall over an ungauged tropical mico-watershed: A downscaling algorithm using GPM data”

I am happy that the authors have made significant improvements. However, there are still a lot of writing issues, which should be corrected before I can recommend for publication.

General comment

There are still numerous writing problems, and a professional writing service is recommended.

Figures: The figure quality is too low to see clearly.

For equations, I would suggest simply using (1), (2) … to indicate the number.

Abstract, Line 13, delete “of” in “the half hourly of …”

Line 17, change “;” to “,” before “which”

Line 18-19, delete “of” for “the original of …”

Line 22, either “difference” or “were”

Line 23-24, what do you mean “normal season”?

Line 35-36, regarding the spatio-temporal distribution of rainfall, a recent study by Su et al. (2020, DOI: 10.3390/atmos11030303) is worthy to be cited, while this study is for China region including both tropical and mid-latitude regions.

Line 51, it should be “… was unable to …”

Line 57, “that” should be deleted.

Line 59, “Most of the downscaling approach was …” -> “Most of the downscaling approaches were …”

Line 70, what does “or” here mean?

Line 71-72, grammar errors exist in this sentence, particularly I do not understand “… are literally have none or …”

Line 74, “by” should be deleted.

Line 79, “effect” should be deleted.

Line 91, “where”? I think it should be “when”

A lot of other writing issues exist, which are not listed here.

Line 526-527, how could the spatial pattern and distribution be increased by an average of 35%? How did you define and get this quantity number?

Author Response

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Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

The readability of this manuscript has greatly improved. The turnaround time is too short for me to provide a thorough review, but I am satisfied that the content is now accessible to many more readers now that the language barrier is reduced. I think this manuscript is OK to proceed to publication in this journal. I encourage the authors to carefully review the language and figures one more time before final publication.