Noise Mitigation of the SMOS L1C Multi-Angle Brightness Temperature Based on the Lookup Table

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper presents a noise mitigation method of the SMOS L1C multi-angle Brightness Temperature based on the lookup table，the topic of this manuscript is attractive. The experiments in this manuscript are sufficient. But the following questions should be considered.

1. The definition of the sensitivity need be expressed, Please give specific derivation to explain why the sensitivity is lowed in the SMOS data.
2. In Figure 4, the STDs of the SMOS TBs for the H and V polarizations are 4.14 K and 3.94 K, whereas those for the SMAP TB are 1.09 K and 1.15 K, how to estimate the noise level should be derived.
3. Equation (1) need more explanation. The significance of the results to the proposed algorithm needs to be emphatically analyzed.
4. Which influence factors of the established comprehensive lookup table except the size in figure (6) will affect the performance of the noise mitigation, and the proposed method can be applied in other data products? Why ?
5. The paper is short of mathematical models and theoretical derivation and analyzation.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. seciton 2:How can RMSE of brightness temperature be obtained from Figure 3.
2. section 2:The spatial matching conditions for SMOS and SMAP data, such as parameters including clear sky, ocean, wind speed, etc., should be clarified.
3. The noise of a single SMOS pixel is relatively calibrated, and the variation range of L-band sea surface brightness temperature is small. For Figure 5, a scatter plot of observed brightness temperature and modeled brightness temperature should be provided to more clearly illustrate the correlation.
4. Expand the forward model described in Section 3.1. Meanwhile, is the model accurate when the incident angle is greater than 60°?
5. Section 3.1. needs to clarify weather and sea surface conditions. For example, whether this method is still applicable under rainfall conditions?
6. Section 3.1. What does the vertical coordinate of Figure 7 represent?The result of the correction should be a first-order fitting result, characterized by the slope and bias.
7. Section 4.1.The paper mentions that the 4K bias between the corrected SMOS brightness temperature and SMAP brightness temperature is due to the calibration differences between the two instruments. Is this influence brought by the forward model in the calibration process?
8. Different incident angles correspond to different salinities in the inversion sensitivity. Please explain whether the method in this paper has a better incident angle range.
9. The method in this paper strongly relies on the background field and the calculation accuracy of the model, and further refinement is needed in terms of innovation.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The paper has been revised. Thanks for the author's diligent efforts. The article is now suitable for publication.