A Multi-Year Study of GOES-13 Droplet Effective Radius Retrievals for Warm Clouds over South America and Southeast Pacific

Round 1

Reviewer 1 Report

In this manuscript, the authors investigated GOES-13 droplet effective radius retrievals over South America and Southeast Pacific. Investigation of the retrieval method for droplet effective radius is very important. However, I think the current form of this manuscript is not acceptable to publish and I request you change several parts of this manuscript. Detailed comments are followed.

 

First of all, it is not clear what the main topic of this manuscript. As mentioned in this manuscript, Painemal et al. (2021) already showed retrieval for effective radius from the GOES-13. How the retrieval method of this manuscript differs from the previous study should be emphasized more. Furthermore, I think that the authors should also present the comparison result when using the retrieval method from the previous study.

 

Next, the authors mentioned the limitations of the retrieval method in this manuscript (e.g., seasonal variation, illumination). I recommend that the authors describe how the retrieval method can be corrected to overcome these limits.

 

Third, as mentioned in this manuscript, previous studies have presented that comparison results between retrieval effective radius and effective radius from in-situ aircraft measurements. In-situ aircraft measurements over the Amazon, such as the GOAMAZON, already exist. I recommend that the author add the comparison results with in-situ aircraft measurements.

 

Fourth, the authors used only the data for four months in each year. Why did not the authors use 12 months of data?

 

Finally, the text of this manuscript was not easy to read. It is recommended to make sentences concise (e.g., use more commas).

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript aims to evaluate the droplet effective radius retrieved by GOES-13 over South America and Southeast Pacific. They found that the results vary with day and season, and the backscattering hemisphere and illumination/viewing configurations are discussed.

 

Overall, this work seems suitable for MDPI Atmosphere. However, Method and Figures must be improved.

 

Major:

Line 244 and Line 284: I am very confused by your sensor view zenith angles. As you stated, they are 10° to 30° in your LUT. However, at Line 284, you stated “θv was limited at below 60°”. GOES-13 is located at 75°W, and therefore the sensor view zenith angles at 75°W, 0°N should be 0°. How do you treat your view zenith angle?

Figures: authors should put more effort on Figures. The texts on each figure are so small that I cannot see them at all. Authors should adjust the zoom to 100% to see if they can see clearly. Authors should also check the text in their figures. For example, in Figure 5a “sector” should be “Sector”. Figure 8, “214” should be “2014”.

The view zenith angle of Modis is also different, which causes different Re retrieval at the center and at the edge. Does this have a considerable impact on your results?

 

Minor:

Line 25: average droplet size is another term, rather than effective radius.

Line 142 and Figure 1: please unify your description in the whole manuscript, 75°W or -75°E ?

Line 254: spatial resolution of 0.63, 3.90, and 11.0 um is 1 km, 4 km and 4 km respectively. How do you interpolate them to 8 km x 8 km grid? Average radiance or average brightness temperature or the others?

Line 313-Line 333: I strongly suggest the authors cite some paper about the comparison between the others geostationary sensor (such as FY-4A, Himawari-8, etc.) and Modis, since the difference here might be due to Modis rather than GOES. In addition, the performance of terra Modis and aqua Modis is also different.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have solved most of my questions.  I think that this manuscript can be published in the present form.

Reviewer 2 Report

All my previous concerns have been well addressed.