Processing and Validation of the STAR COSMIC-2 Temperature and Water Vapor Profiles in the Neutral Atmosphere

Round 1

Reviewer 1 Report

The manuscript "Processing and Validation of the STAR COSMIC-2 Temperature and Water Vapor Profiles in the Neural Atmosphere" is a very interesting validation of the new product STAR for COSMIC-2 GNSS radio-occultation mission. In my opinion, article is well-written and clear, and the research is sound. I recommend minor changes to the text and figures which I list below. Congratulations to the authors.

Minor changes:

- Lines 150-151 something seems wrong in the link, please check
- With 5x5 grid it means 5-degree latitude and 5-degree longitude grids? Please clarify this.
- Line 415. SR is not defined before.
- In Figures, please add proper color legend, not just explain it in the caption.
- Fig 14. It sas "similar to 14". I guess it should say "13" instead.
* Lines 740-741. There is a different font-face.
* The acknowledgments are not acknowledgments.
* Some figures are "streched" (figure 19) or a bit blurry (figure 15, for example). It would be nice to improve their quality.

Author Response

I have uploaded my point-to-point responses to reviewer#1's comments below.

Author Response File: Author Response.docx

Reviewer 2 Report

The article deals with the issue of the system for observing climatic conditions such as temperature profiles and specific humidity of water vapor. The authors deal with a very current issue that can contribute to the monitoring of the current situation in meteorology and the monitoring of climate changes and predictions of their development. Considering current developments, I consider this work to be important and interesting for readers. The authors also address the Data Processing and Validation System and evaluate the standard deviations and uncertainties of the observation.

 

In the introduction, knowledge from other works and other studies is presented. COSMIC-2 data characteristics and initial validation results for the UCAR-derived COSMIC-2 data products conducted by STAR are presented in the next part. In-situ radiosonde data and MW and IR satellite data are shown later in the article. The next part introduces STAR's one-dimensional variation (1D-Var) approach to convert the refractivity to temperature and moisture profiles. There are comparisons of STAR 1D-Var products with the collocated radiosondes. 1D-Var derived temperature and water vapor profiles to compute the simulated brightness temperature (BTs) is used for Advanced Technology Microwave Sounder (ATMS) and Cross-track Infrared Sounder (CrIS) channels in the lower stratosphere and upper troposphere, and the troposphere and compared to the collocated ATMS and CrIS measurements.

 

This study demonstrates that the STAR GNSS RO Data Processing and Validation System is very useful for monitoring the measurements and retrievals and the observation uncertainty from the multiple RO missions, which are critically important for optimizing the usage of RO data in the numerical NWP system through data assimilation.

It is a well-developed work, but the authors did not avoid several formal errors.

Comments:

Scalar quantities should be written in Italic style and Matrix quantities should be written in bold style. But the editor will probably deal with that during proofreading. For example, on line 219 and 220, it needs to be corrected. Please check the full article. Check equation 6 and 7.

On line 674 there is "Km" and it should be "km".

On line 313 "Jun" should be "June"

The images in the article are not in a uniform style. For example, images 13 and 14 have too much text compared to the other images. It looks bad.

There is a blank line between references 31 and 32.

Author Response

Here I upload my point-to-point response to reviewer#$2's comments.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors have comprehensively validated the accuracy of temperature and water vapor profiles derived from COSMIS-2 data. Satellite radio occultation products are indispensable for weather forecast and climate research, and the continuous assessment of the products are quite important and valuable. The authors describe the processing of the COSMIC-2 profiles and show the validation results in detail. Basically, this manuscript is well organized and worth publishing with some minor revisions. This manuscript seems to be redundant at some places, and some figures need to be redrawn. 

 

1) Line 21-24, 82-86:

The authors say "to better quantify how the observation uncertainty from clock errors and geometry determination may propagate to ...", but the "clock errors and geometry determination" are not mentioned in the following text at all.

 

2) Line 204: "(see Figure 8)"

There is no information on wavelength in Fig.8. Is "Figure 8" wrong? Figure15?

 

3) caption of Figure 8:

There is no explanation of red, green and blue lines.

 

4) Figure 8:

Why don't the authors show the part below 13 km height? The height range is not consistent with the other figures. 

 

5) Line 375-377: "The magnitude of the temperature averaging kernels ... above 25 km."

Where is this shown?

 

6) Figure 9:

Although the authors divide the region into 45-20N, 20N-20S, and 20-45S for Figs.3-7, Figure 9 shows different partitions: 45-30N, 30-0N, 0-30S, 30-45S. They are inconsistent with each other. The seasonal variations in 45-20N and 20-45S in Figs.3-7 are large, and the target region should be divided into the 4 or more zones. 

 

7) Figures 10-12:

The height range is different from each other. Basically the height range should be the same. You should not change the height range of figures without reasons.

 

8) Line 496-497:

The assimilation from March 2020 did not make the bias smaller. Why?

 

9) Figure 16:

How large is the difference between E1 and CrIS? Shouldn't the authors show it?

 

10) Line 678-679, 691-693:

The bias of ECMWF does not look significantly higher than the others, especially for CH08-09 and CH20-21.

 

11) Line 699-701: "which is due to ... retrieval algorithms."

I don't understand this reason. Please explain it in detail.

 

12) Figure 19:

Why don't the authors show error bars? This is different from Fig.18. And, the bias of E1-E2 is also large, but this is not mentioned in the text.

 

13) Line 769-775:

This part is not necessary to be described in Conclusions.

 

Minor comments:

14) Equation (1):

There is an arrow instead of a plus in the right side.

 

15) Line 331, 337, 337: 

"The magnitude of temperature A" should be "the magnitude of A for temperature".

 

16) Line 333: 

"above 9 km" -> "above 10.5 km" is correct?

 

17) Line 412:

What is "V/V"?

 

18) Line 420: 

COSMIC -> COSMIC-1 ?

 

19) Figures 8-10:

It will be better that the green lines show only standard deviations, rather than mean difference +/- standard deviation.

 

20) Table 1:

Table 1 is unnecessary because this information is written in Fig.11.

 

21) Line 496:

What is "O-B"? It is explained in Line 628, but it must be placed in Line 496.

 

22) Line 584:

fo -> for ?

 

23) Line 660:

(CH07-11) -> (CH07-12) ?

 

24) Line 684, 690:

"relatively" is unnecessary.

 

Author Response

Here I upload my responses to reviewer#3's comments.

Author Response File: Author Response.docx