Comparative Analysis of Striping Noise between FY-3E MWTS-3 and FY-3D MWTS-2
Round 1
Reviewer 1 Report
Comments on “Comparative analysis of striping noise between FY-3E MWTS-3 and FY-3D MWTS-2”
The manuscript compares the difference of striping noise (SN) in the measurements of FY-3E MWTS-3 and FY-3D MWTS-2, which is paid more attention before their being applied into data assimilation system. The method of the manuscript used is convincible which has been applied in analysis the measurements of some other microwave radiometers. The results are generally validated by collocated data from the two sensors at some area of the Pacific Ocean in a few days of 2021, though the representativeness of the results is weak relative their coverages of two sensors and duration of the observations.
The main questions and concerns about the manuscript are listed below:
1. Page 2, lines 57-58, from what the conclusion of “Nevertheless, while increasing the number of FOVs is conducive to a higher spatial resolution, it also adds additional noise, specifically known as striping noise” is derived? If the reason producing SN can be traced certainly, what is it?
2.You say “It is believed that the improvement in calibration accuracy and instrument sensitivity of MWTS-3 are the main reasons for the reduction of striping noise” (P10, lines 221-222), if so, why the noise is striped? In other words, you mean that calibration accuracy and instrument sensitivity are striped? It is obvious impossible for the two parameters.
3. In Fig 9 in P11, the characters of correlation coefficients between channels for the two sensors are different, but some channels of MWTS-3 are highly negative correlation, which it also needs to be identified for tracing the reasons.
4. The shade area in the Fig 11 is not clearly stated for the differences computation and the titles of (a) and (b).
5. From the table 1, NEDT of MWTS-3 are much smaller than those of MWTS-2, But in Conclusion of P12, the striping noise intensity of channels 7-13 are general the same for the two sensors, which means the sensitivity of the sensor is not the sources producing SN. IF the methods used deriving SN or the models used for O-B might contribute to the phenomenon of SN?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Thank you very much for the paper which is very interesting for fugure radiometer instruments development. Please find below my comments:
1) Phrase in lines 12-13-14 nnot fully understood, I encourage to review it
2)Line 15: Are you referrring to MWTS-2 or MWTS-3?
3)Line 24, the number of observations depend obviously on the latitude, please specify, which ones are you considering
4) Line 32 Why are you considering the world’s first early-morning-orbit satellite? There are other polar satellites at the similar LTAN. What makes it unique?
5)Line 57: Can you confirm that by the number of FOV you refer to the number of measurements (i.e. related to the integration time?) or to the resolution of the real aperture. Could you please include a brief explanation?
6) line 59 Can you please explain the condept of stripping noise as some readers may not be familiar with the concept?
7) line 61: Similar with the "O-B" concept, could you please include a brief defintion
8) line 66: Could stripping be related to the short term stability of the references used on the instrument for calibration since it is constant along the scan and the calibration is generally done each scan? (please analyse)
9) line 88 (but in general for the complete paper): Please try to move the figures closer to the part of the text where they are cited, otherwise it makes the reading quite difficult
10) Table 1: There seems to be channel 3 for MWTS-2 and channel 5 for MWTS-3 missing
11) Stripping noise does not seem obvious in figure 2
12) Figure 2: Those channels are missing from table1
13) line 188-189: Can you please specify? As stated above both channels have a relatively similar stripping noise
14) Line 190 Please explain the differences between Fig5 and Fig4
15) lines 209-211 Looking to the figure it seems that the stripping noise is quite similar and below 0.1 except for the highest frequency channels
16) Line 220 If stripping noise would be related to calibration, the number of FOV would not have an influence to the stripping noise. Could you correlate the stripping noise with the reference values used for instrument calibration for each scan?
17) Figure 8: Fig 7 shows a higher stipping noise for channel 10 on MWTS-2 than on 14 for MWTS-3, however the plot in Fig.8 seems to show that the noise in MWTS-2 is smaller. Could you please explain why?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear Authors, thank you very much for submitting your paper.
The paper presents the methodology for the computation of the striping noise on the channels of FY-3 MWTS-3 and FY-3D MWTS-2.
After the introduction and the overview of the methodology, some results are presented and compared between the two instruments.
I recommend to have a look at the following comments:
1. Eq. 1:It is not clear if the Amatrix will contain all the obesrvations for all channels or if there will be an A matrix per channel.
2. line 190-191: It says that the striping noise on MWTS-2 is stronger that MWTS-3 and it is quite visible in Fig. 5. However, Fig. 6 the peak of the striping is on MWTS-3, which apparently is in contrast with the description of Fig. 5. I suggest to plot the striping to enphasize the behaviour on MWTS-2.
3. I recommend also to have a look at the work of Dr. Nigel Atkinson from the UK Met Office for the computation of the striping index.
“Striping” tests for microwave sounders
Satellite Applications Technical Memo 17
Nigel Atkinson
Satellite Data Products and Systems
07 May 2014
:
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The questions listed in the last review has been correctd or explained clearly.
