Scale Analysis of Typhoon In-Fa (2021) Based on FY-4A Geostationary Interferometric Infrared Sounder (GIIRS) Observed and All-Sky-Simulated Brightness Temperature
Round 1
Reviewer 1 Report
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Comments for author File: 
Comments.pdf
Needs a solid review. Numerous grammar errors throughout
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
This manuscript aims to assess the performance of the FY4A GIIRS instrument through all-sky simulations using a tropical cyclone case study (In-Fa in 2021). The findings demonstrate that the all-sky simulations, based on ERA5 and FNL datasets, effectively replicate the structure and intensity of Typhoon In-Fa. Additionally, it is observed that the dominant features of Typhoon In-Fa are predominantly at a large scale, but the proportion of large-scale features decreases while the amount of small-scale information increases during the Typhoon stage. The subject matter of this manuscript aligns with the scope of the journal. This paper has the potential to be valuable, particularly in the context of all-sky data simulation and scale analysis, which are crucial for tropical cyclone forecasting. However, there are a few significant concerns regarding the comprehension of the presented results, as discussed below.
Major issues
1. The authors did not provide specific information regarding the application details of ERA5 and FNL. It is unclear whether both analyses were conducted at the same horizontal resolution. The simulated brightness temperatures (Figs. 3 & 6) derived from FNL exhibit more refined spatial characteristics compared to those based on ERA5. This discrepancy may be attributed to the utilization of ERA5 products with a coarser resolution. In light of this, it is recommended that the authors repeat the experiment using ERA5 at the same resolution as FNL.
2. In the field of meteorology, systems with spatial scales of 103 km are commonly referred to as large-scale systems. To avoid any confusion, it is crucial to explicitly define what is meant by "large scale" and "small scale" features in the analysis of Figure 6-8 and the abstract. Based on my interpretation, the authors identified the "large scale" features as the Fourier signals with wavelengths greater than 336 km in Figure 8. They attempted to establish a connection between these large-scale features and easterly waves and monsoon troughs. However, easterly waves and monsoon troughs are not clearly observed in Figure 6.
3. A subsequent inquiry regarding the preceding statement arises. In Figure 7, the method employed to establish the storm center line remains ambiguous. Is there consistency in the identified storm center lines across different datasets and time periods? Furthermore, what specific information does the x-axis encompass? To address these concerns, the authors may consider including a depiction of the storm center line in Figure 6.
4. In the analysis presented in Figure 8, the authors have observed that as the tropical cyclone (TC) progresses from the tropical depression (TD) stage to the typhoon (TY) stage, there is a decrease in the proportion of large-scale features, while the amount of small-scale information increases, particularly within a radius of 336 km. As mentioned earlier, the simulated brightness temperature (BT) based on ERA5 data appears to be smoother compared to the observed BT and the simulated BT based on FNL data. Therefore, it would be expected that the proportion of large-scale features would increase, while the amount of small-scale information would decrease for ERA5. However, this expectation seems to contradict the results presented in Figure 8. It would be helpful if the authors could provide an explanation of how the observed increase in "small-scale information" is reflected in Figure 6.
5. The figure captions lack sufficient detail, making it challenging for the reviewer to comprehend the figures. For instance, in Figure 1, the authors should explicitly specify in the caption the meaning of the colors and numbers represented in the plot.
Minor issues
1. Line 146: Did the authors apply the default parameters, or other parameters, for the input of the cloud ice water scheme. How reasonable is this setting?
2. Line 158: what do you mean by “description” here?
3. Line 204: Redundant “corresponding to”
4. Figure 6: while discussing the performance of all-sky simulations in terms of correlation coefficients, it is always important to include their statistical significance.
There are still a little space to polish.
Author Response
See attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
General comments: This paper describes the comparison of BT of Typhoon InFa for different RTTOV simulations in the FY4A GIIRS observation space, which is of good quality for the mid-low observation application. The current written English seems good quality. However, several issues should be carefully considered as following.
Comment1: Line 41-42, “ ... as the all-sky approach.”, the main strategy of “all -sky approach” that related to your research should be briefly noted here, e.g., the bias correction tending more to background or observation, or the WF correction related to some factors? I think this could be helpful for broader reading.
Comment2: Line 72-73 “However, ... has not been carried out yet ...” and Line 75-77 “In order to ...”, the motivation and research gaps seem no very clear for this study, I think which can be improved.
Comment3: Line 102-104, where this information come from? The information source should be add here.
Comment4: Line 134-141, the most important numeric parameter of RTTOV for your study should be mentioned here to focus your method novelty.
Comment5: In section 2, the FNL and ERA5 datasets have never been mentioned, do they directly used in RTTOV without any additional handling? Please clearly address this issue during this section.
Comment6: Line 157-159, I can not see “The BT simulated with FNL data is apparently smaller than that with ERA5 and the observation around the typhoon eye” but only lower BT in FNL for Figure 3.
Comment7: Line 161, does the “clouds” here means the lower BT of GIIS? Can all the lower BT of centimeter wave over land be the cloud, and why? Please clearly note this here. In addition, where is Hunan province ? Please note this in Figure 3. Also, please make sure the description texts without figure indexes for Fig. 3. and Fig. 5. are proper.
Comment8: Line 217, “Fourier analysis” has used without one explain, e.g., “In order to investigate the scale-depended characteristics of ....., the Fourier analysis ..” which should be explained or predefined here.
Comment9: Line 231-234, what are the inside and outside observations ? Please revise these texts.
Comment10: Line 273-275, according to your results, the scale depended BT variances can be related to the stage occurrence time of Typhoon, then observation thinning can be conducted, e.g., on the mid-lower channel data, right? Can the stage occurrence time of Typhoon be indicate by BTs themself or other resources ?
Comment11: Finally, my concern is that can this scale relation be robust for typhoon study, and can this mid-low BT datasets be used for the cases over land ? Please clearly address these issues during your last section.
Comment12: Wrong superscripts in Line 172 can be observed.
The current written English seems good quality.
Author Response
See attached file.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors have addressed my previous concerns. Moderate English grammar editing is needed.
Moderate English grammar editing is needed. There are too many instances of poor grammar to document individually (especially given the short response time allotted by the journal to provide a quality review). I recommend that the authors use an editorial service that specializes in English grammar.
Author Response
Thank you very much for your excellent suggestions. The English language quality of this paper has been edited by the Nanjing Hurricane Translation.
Reviewer 2 Report
The revised manscript is fine. Authors replied satisfactorily all questions.
Author Response
Thank you very much for your excellent suggestions！
