Carbon Dioxide Retrieval from TanSat Observations and Validation with TCCON Measurements

Round 1

Reviewer 1 Report

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Comments for author File: Comments.pdf

Author Response

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Reviewer 2 Report

The manuscript present the retrieval of the XCO2 from the TanSat observations using the ACOS algorithm. The authors process a large data set showing the ACOS algorithm is also capable to evaluate XCO2 retrieval from TanSat measurements. It is a good paper and easy to read, I think the paper could be published with minor changes mainly in validation section.

Specific comments:

- I suggest to include the discussion of section 2.2 together with section 4, I think that two section about the data set validation may confuse the reader.

Minor comments:

- line 161: typo in the partial derivative of F(x);

Author Response

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Reviewer 3 Report

The manuscript addresses an important issue - the validation of satellite CO2 measurements by the TANSAT satellite using the ACOS algorithm based on TCCON network data and a special measurement campaign. Validation of various measurement methods and spectral data inversion algorithms is necessary and should be carried out regularly. The obtained methodology for correcting the results and the results of comparison with independent measurements showed a good agreement between satellite and other data. The manuscript, after a little revision, may be published.

Line 54 reads “a few tens of a percent”. The authors probably meant “tenths”.

Line 65, “both satellite”, is desirable to clarify.

Line 243, relastion (4). The appearance of DFS in the denominator is not clear, the signal is already taken into account in F(i).

Line 331 “FPA”, Line 487 “TG” - authors should clarify the abbreviations.

Lines 477-485 Analyzing the reasons for the differences, it is also advisable to consider the different vertical sensitivity of space and ground-based measurements to the CO2 total column.

Lines 460-509, Conclusion
In this analysis, it would be useful to compare the obtained results with the requirements for the precision of CO2 measurement. i.e. https://www.wmo-sat.info/oscar/variables/view/39, or http://ceos.org/document_management/Virtual_Constellations/ACC/Documents/CEOS_AC-VC_GHG_White_Paper_Version_1_20181009.pdf

Author Response

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Reviewer 4 Report

line 45 satellite instead of Satellite
line 69 please explain O2A
line 72 developed instead of develop
line 104 and 106 Sect. instead of sect.
line 113 what is the orbit inclination?
line 191 please explain LMDZ
line 214 it is strange that TCCON uncertainty is estimated by a constant. Do they give no error bars?

Figure 5 the y-label is not correct. It should be a delta.

line 487 please explain TG

Author Response

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Round 2

Reviewer 1 Report

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Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx