Improving the Operational Simplified Surface Energy Balance Evapotranspiration Model Using the Forcing and Normalizing Operation

Round 1

Reviewer 1 Report (Previous Reviewer 3)

In this study, an improved approach is developed for the parameterization of the Operational Simplified Surface Energy Balance (SSEBop) model using the Forcing and Normalizing Operation (FANO), having as main objectives 1) outline the formulation of the FANO parameterization in SSEBop, 2) describe the implementation of the updated model in two computing platforms, 3) present evaluation results using station-based ET measurements and water balance ET approaches, and 4) feature illustrative ET maps in different parts of the world.   The methods are appropriate. The results and discussion are clearly presented. The conclusions in this manuscript are supported by the experimental results. The references are based in current papers.   The manuscript is well written and it is easy to comprehend it. Overall, the presented research could be valuable to other researchers in this field.   The authors have done good work in corrections of the manuscript. I support its publication.

Author Response

Thank you!

Reviewer 2 Report (Previous Reviewer 2)

It can be considered for publication in Remote Sensing.

Author Response

Thank you!

Reviewer 3 Report (New Reviewer)

In the study entitled “Improving the Operational Simplified Surface Energy Balance Evapotranspiration Model using the Forcing and Normalizing Operation” an improved approach to the parameterization of the Operational Simplified Surface Energy Balance (SSEBop) model using the Forcing and Normalizing Operation (FANO) is developed. Further, the study describes the implementation of the updated model in two computing platforms, presents evaluation results using station-based ET measurements and water balance ET approaches, and features illustrative ET maps in different parts of the world. The study needs the following Minor Revisions before publication.     

1. The abstract need to be revised. It lacks providing sharp/clear information about the article for example the problem statement, conclusion, and limitations of the study need to be included. 
2. Figure 1: It is presenting only two parameters from the legend on the map. If it is enough, then what is the need to write the rest of the parameters i.e. HUC8 selected, HUC8 FANO, HUC8, etc?
3. Figure 3: Isn’t it better to replace the 365 days of the year in the horizontal axis with the month names like Jan, June, December, etc for better understanding?
4. Table 3: Please explain the value of “r”. Same for table 6.
5. Please explain, how this study is novel in research as this kind of work has already been done in the literature.
6. 2.2.1: It would be better to replace the heading “Data” with “Study Area”.
7. Please revise figure 11 as it is not readable. 

Author Response

Responses to review #3: Minor Revision

Manuscript: RS-2142728

Title: Improving the Operational Simplified Surface Energy Balance Evapotranspiration Model using the Forcing and Normalizing Operation

 

Reviewer comments are in black and response in blue/italics.

1. The study needs the following Minor Revisions before publication.    

The abstract need to be revised. It lacks providing sharp/clear information about the article for example the problem statement, conclusion, and limitations of the study need to be included.

 

Response:

Done. Abstract has been expanded from about 200 to 300 words to stress the objective and include key details on the new technique and improved results.

 

2. Figure 1: It is presenting only two parameters from the legend on the map. If it is enough, then what is the need to write the rest of the parameters i.e. HUC8 selected, HUC8 FANO, HUC8, etc?

Response:

We revised the caption for clarification. Revised caption is shown in yellow.

Figure 1. Location of eddy covariance (EC) towers used in this study; qualified eight-digit Hydrological Unit Code (HUC8 selected, HUC8 FANO) boundaries for the one-to-one evaluation of two versions of SSEBop model (red, HUC8 selected) and additional qualified HUC8 with SSEBop v0.2.6 (FANO) (green, HUC8 FANO); unqualified watersheds for water balance-based ET evaluation are shown in blue (HUC8). FANO procedure test site covering the western part of Nevada (Landsat path/row: 043/033) along with the six regions of the conterminous United States are displayed.

 

3. Figure 3: Isn’t it better to replace the 365 days of the year in the horizontal axis with the month names like Jan, June, December, etc for better understanding?

 

Response:

Done. Good suggestion.

 

4. Table 3: Please explain the value of “r”. Same for table 6.

 

Response:

Table 3 is revised to define r as follows (yellow highlight)

Table 3. Summary of HUC8 ETa comparison between SSEBop v0.1.7 and SSEBop v0.2.6 (FANO) with water balance (WBET). The Pearson correlation coefficient (r) shows the degree of association between the two versions of SSEBop and WBET.

Table 6 caption is revised as follows (highlighted):

Table 6. Overpass actual ET (ETa) comparison between SSEBop and flux tower categorized by landcover (as reported by Ameriflux). SSEBop was forced with the climatology Gridmet 1981-2010 ETr without any scaling factor.

 

5. Please explain, how this study is novel in research as this kind of work has already been done in the literature.

Response:

The innovation is specific to the SSEBop model and not referring to the wider ET modeling efforts. The following statement is included in the revised next to the innovation statement to clarify what the innovation involves.

“The main innovation involves the elimination of the high NDVI (Normalized Difference Vegetation Index) requirement and replacing it with a deterministic equation that expands the spatiotemporal coverage of the SSEBop model.”

 

6. 2.2.1: It would be better to replace the heading “Data” with “Study Area”.

Response:

Agreed. Replaced with “Study Area”. It makes sense as data was already used earlier under 2.1. Thank you.

7. Please revise figure 11 as it is not readable.

Response:

Uploaded a revised Figure 11 with improved readability. Thank you for the suggestion.

 

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This work is about improving the parameterization scheme of an existing model, SSEBop, for its application over arid and semi-arid regions. I did not find any major shortcomings in the work. There are some minor changes observed that require attention, especially the acronym FANO. 

Comments for author File: Comments.pdf

Reviewer 2 Report

In this manuscript, the author developed an improved approach to the parameterization of the Operational Simplified Surface Energy Balance (SSEBop) model using the Forcing and Normalizing Operation (FANO) and evaluated it over the conterminous United States. This study is innovative and meaningful, but there are some concerns which needs to be addressed, before it should be considered for publication in Remote Sensing.

Major comments:

1.        Line 220: The strong inverse linear relationship between ∆Ts*/dT* and ∆NDVI* has showed in this example (elevation ranges between 1,200 m and 1,500 m and specific date), but I would more concern about the question that does the strong linear relationships exist in other region, dates and other elevation levels? Besides, if there exists some figures or charts can illuminate the FANO constant f value with 1.25 for the general region.

Minor comments:

1.        Line 62，actual ET should be rewrite as ETa.

2.        Figure 1: the color of the legend is illegible, please improve the picture quality.

3.        Table1: parameter “dTs*” should be revised as “ΔTs*”, in order to keep consistent with “ΔTs*/dT*”.

4.        Line 269: “Note that the top-of-atmosphere NDVI was found to be about 12% lower than the SR NDVI for the same vegetation cover”, please add reference for this conclusion.

5.        Figure 4: The dotted box of “Tc*(FANO eq.9)”, should be revised as “Tc*(FANO eq.8)”, right?

6.        Figure 6: In the first figure, the scale spacing of the horizontal should keep consistent with other figures.

7.        Table 4: The index of STD should be detailed in text when it first showed up, please add.

8.        Line 613: “The blue line shows……”, in my opinion, when you explain the result at cropland and grassland sites, you should point out which one of the pictures you are explaining. Please add the relevant statements.

Reviewer 3 Report

In this study, an improved approach is developed for the parameterization of the Operational Simplified Surface Energy Balance (SSEBop) model using the Forcing and Normalizing Operation (FANO), having as main objectives 1) outline the formulation of the FANO parameterization in SSEBop, 2) describe the implementation of the updated model in two computing platforms, 3) present evaluation results using station-based ET measurements and 104 water balance ET approaches, and 4) feature illustrative ET maps in different parts of the world.
In the introduction, highlights are missing to attracting the attention of the reader for novelty and relevance of the proposed contribution.
Conclusions could explore experimental results in a more consistent approach and give an assertive response to the proposed objectives.