Tracking Evapotranspiration Patterns on the Yinchuan Plain with Multispectral Remote Sensing

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comments

The proposed validation method is not appropriate, as ET, ETr are distinct variables. ET may approach ETr under conditions of abundant water availability, but is generally lower than ETr (and pan evaporation) when the surface is under water stress. Therefore, bias shouldn’t be used for deviations between ET and ETr.

The authors calculate the trend of ET based on 22 images irregularly spaced between 1989 and 2020, all in either August or September. Although they were able to capture changes in ET due to land cover change, the sample is not appropriate for calculating trends, since several years are missing, what could significantly change the trend over areas with constant land cover.

Specific comments

Line 45: “… researched and validated”

Line 55: The SSEBop model doesn’t require hourly meteorological data, but it rather uses daily aggregations, such as mean net radiation and max temperature, for example.

Lines 104-117: It is not clear if the authors use reference ET (ETr) derived from atmospheric variables (such as air temperature, radiation, wet-bulb temperature, etc.) or measured pan evaporation to validate ET from geeSEBAL. They should clarify this point.

 Table 1: The authors do not describe how they reached the selected percentiles for the endmembers criteria.

Lines 156-181: equations for specific humidity and saturation vapor pressure are displayed but it is not described how they fit into the calculation of ET in the geeSEBAL model.

Equation 9: RMSD

Line 235: “… geeSEBAL…”

Line 269: “… geeSEBAL…”

Lines 345-349: It is uncommon to see impervious surfaces with higher ET rates than grasslands. The authors should explore the reasons for this unexpected result.

Comments on the Quality of English Language

There are typos and grammar errors in the text that must be addressed.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The study titled “Using Multispectral Remote Sensing to Track Evapotranspiration Patterns in the Yinchuan Plain” aimed to assess the ET pattern using the GEE platform in the Yinchuan Plain. Overall, the quality of the paper is good but can be improved as follow as the following suggestions:

• explain the full remote sensing model achieve good inversion results in semiarid and humid areas?

Problem statement and research gap should be more clearly mentioned in abstract and conclusion sections. In addition, why these species objectives of the study are selected for research gap point of view. 

• title can be improved further.

• Explain that single-layer models do not need to distinguish between ET exchanges from soil and vegetation.

• Provide the benefits, challenges, and limitations of single-layer models and double-layer models and also effective areas where they can be used.

• Did the study validate the geeSEBAL model? If the model has been validated, please mention the validation result.

• Typo mistake in 2.3 Heading.

• On what base is the SEBAL algorithm used? And also mentions the challenges and limitations of the SEBAL algorithm.

• Mention the reason why R2 was not as high as expected in four meteorological stations in large ET comparison, and the R2 showed a higher correlation for most of the stations in small ET values, reaching up to 0.82.

• Mention the standard value of R2.

• Generally, the standard value of R2 is 0.9, but your calculated R2 values are less than this range, then how is your model accurate?

• Compare the calculated R2 values with standard R2 value

Comments on the Quality of English Language

Carefully proof read the complete document for language improvement 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have presented a precise case study of evapotranspiration using remote sensing data that could be an interesting work for future climatic studies by incorporating the remote sensing. The work should be significantly revised by addressing the following comments:

Abstract section

1. The abstract section must include the research gap or problem study before writing the aim of the study.

2. Enlist the key objectives of the study to elborate the scope of the study.

3. Conclude the abstract section with global significance and application of the study.

Introduction section:

4. The start of introduction section with the similar statement as of the abstract is not recommended.  Please revise the start of introduction section (lines 28-29) for better quality of the manuscript. 

5. Discuss the various studies apply on agricultural plains around the globe in the literature  

Material and methods section:

6. Redraw the figure 1 as it should include the territory or regions and global map with scale or part of china province.

7. The figure 1 caption could be in a more detailed manner to describe the variation in the region and its relevance with the study.

8. Table 1 caption must include the explanation of vaious parameters used in the study.

Results section

9. The figure 3 could be revised with various parts like a to f parts and caption should be rephrased accordingly. 

10. Figure 4 caption must describe  the various colours used in graphs and its effect on results range.

11. Figure 5 should be compared and caption must adress all the points comprehensively.

Discussion section:

12. Figure 10 should be cropped to avoid the unnecessary details and screenshot details. 

Author Response

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Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for addressing my concerns. See below for additional thoughts and suggestions:

Item 2.2. Data Sources: For improved readability, provide a table with a description of the stations, including location, type of instrument, data acquisition range, time interval etc.

Comment 7: The authors still do not describe where the actual vapor pressure and relative humidity are used in the geeSEBAL model. Is it necessary to calculate net radiation or something else? They should detail it more explicitly.

Comment 11: Thank you for explaining the reason for impervious areas having higher ET rates than grasslands. I understand this will be a question for the majority of readers. Therefore, I suggest that the authors add this explanation to the manuscript.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper has been revised accordingly 

Author Response

Dear reviewer, thank you very much for your recognition of our work. In future research, we will further investigate the issues identified in the current study with the aim of proposing more comprehensive solutions.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have significantly revised the manuscript. However, a few comments to improve the overall quality of the manuscript are as follows:

1. add the keyword: hydrological cycle

2. Introduction section Lines 91-92: "The Yinchuan Plain area is an important agricultural hub in the Yellow River Basin, but it lacks high precision long-term meteorological data". The statement must be rephrased to explain the various aspects of the study area and how this region is termed an agricultural hub?

Material and Methods section

3. subsection: Study area: Figure 1: label the figure with cities or towns to get an idea of nearby locations in the study area.

Author Response

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Author Response File: Author Response.pdf