The Uncertainty Analysis of the Entrance Pupil Irradiance for a Moon-Based Earth Radiation Observation Instrument
Round 1
Reviewer 1 Report
The manuscript analyses the uncertainty of the entrance pupil irradiance for a Moon-based Earth radiation observation instrument. This is an interesting and meaningful topic for realizing the potential of the Moon-based platform. However, there are still several defects that need to be clarified by the authors.
Specific comments:
1. The Moon-based Earth radiation observation instrument in this manuscript refers to the active cavity radiometer. Although the radiometer can effectively measure the contribution of the Earth’s outgoing radiation in the Moon’s direction, that is the longwave and shortwave radiation. However, for scene-type information and cloud identification, high-resolution detectors, such as multispectral imagers, are required. So, did the authors take this issue into consideration? You can add appropriate related introductions.
2. In the calculation of entrance pupil irradiance, the ERBE ADMs are used. Did you consider using the CERES TRMM ADMs? The CERES TRMM ADMs are more recent and more accurate than the ERBE ADMs.
3. Sections 4.2 and 4.3 show the potential applications of Moon-based data and the dynamic performance of a simplified Moon-based radiometer, but their relationship with uncertainty is confusing, please clarify further.
4. The table number is wrong, please modify it, see line 586 of “Table 2” and it should be “Table 4”.
5. The format of the figures is not uniform, such as the fonts in Figures 17 and 18, please check and modify.
6. Please add the links or URLs of the datasets in this manuscript, such as CERES data products in Figure 17.
7. There are still some unclear expressions and some minor grammatical problems in the work, please correct them carefully.
No.
Author Response
Response to Reviewer 1 Comments
Point 1: The Moon-based Earth radiation observation instrument in this manuscript refers to the active cavity radiometer. Although the radiometer can effectively measure the contribution of the Earth’s outgoing radiation in the Moon’s direction, that is the longwave and shortwave radiation. However, for scene-type information and cloud identification, high-resolution detectors, such as multispectral imagers, are required. So, did the authors take this issue into consideration? You can add appropriate related introductions.
Response 1: Thank you for your comment and the related introduction has been added in Section 4.3. An Imaging Spectroradiometer must work with the radiometer simultaneously to provide accurate scene type, cloud, and aerosol information. The data of the Imaging Spectroradiometer will be used to invert the cloud characteristic parameters in different observation instrument-viewed regions, to facilitate the selection of ADMs and the processing of the Moon-based data. The instrument's setup is similar to that of the EPIC on board the DSCOVR satellite (Su et al., 2020).
Su, W.; Minnis, P.; Liang, L.; Duda, D.P.; Khlopenkov, K.; Thieman, M.M.; Yu, Y.; Smith, A.; Lorentz, S.; Feldman, D.; et al. Determining the daytime Earth radiative flux from National Institute of Standards and Technology Advanced Radiometer (NISTAR) measurements. Atmos. Meas. Tech. 2020, 13, 429–443.
Point 2: In the calculation of entrance pupil irradiance, the ERBE ADMs are used. Did you consider using the CERES TRMM ADMs? The CERES TRMM ADMs are more recent and more accurate than the ERBE ADMs.
Response 2: Thank you for your comment. The ADMs are used to achieve the conversion of the measured radiance to the more energetically relevant quantity of radiative flux, or irradiance. Due to the TRMM orbit being restricted to 38.8°S – 38.8°N, the CERES TRMM ADMs are applicable only for tropical regions. In other words, for the region (> 40°N/S), such as the ice and snow scenes in the South and North Pole, CERES TRMM ADMs did not provide usable anisotropic data. The ERBE ADMs used in this work were derived from the Nimbus 7 Scanner and this set ADMs is still being used in CERES data products. Although there exist some deficiencies in the detailed description of the changing characteristics of ADMs, it is a relatively mature, globally covered, accessible dataset for converting the radiance to a flux estimate when studying the ERB on a macro scale, like the Moon-based platform, and still reflects the main features of the research issues. In addition, we will further consider using CERES TRMM ADMs for the follow-up research.
Point 3: Sections 4.2 and 4.3 show the potential applications of Moon-based data and the dynamic performance of a simplified Moon-based radiometer, but their relationship with uncertainty is confusing, please clarify further.
Response 3: Thank you for your comment and suggestion. The Moon-based Earth radiation observation, as a potential platform, is expected to improve and enrich the current Earth radiation budget (ERB). In this work, the uncertainty of the instrument’s Entrance Pupil Irradiance (EPI) is analyzed, which is important for the design of the observation instrument and the interpretation of Moon-based data. So based on the uncertainty analysis of irradiance, the potential applications of Moon-based data and the dynamic performance of a simplified Moon-based radiometer are introduced in Sections 4.2 and 4.3. Besides, by the extracting linear trend of the Moon-based simulated hourly shortwave and longwave EPI time series, results reveal that the Moon-based observation data can effectively acquire the overall linear trend of OLR and OSR. Besides, the effect of uncertainty on the EPI only changes the intercept of fitted curves without changing the slope. The simplified dynamic response model verifies the detectability of the Earth's outgoing radiation by the MERO instrument, and it is important for correcting and reducing the uncertainty of the Moon-based data.
Point 4: The table number is wrong, please modify it, see line 586 of “Table 2” and it should be “Table 4”.
Response 4: Thank you for your comment. We have clarified it and checked all tables.
Point 5: The format of the figures is not uniform, such as the fonts in Figures 17 and 18, please check and modify.
Response 5: Thank you for reviewing our manuscript. We have unified all the figures and checked the entire manuscript in detail.
Point 6: Please add the links or URLs of the datasets in this manuscript, such as CERES data products in Figure 17.
Response 6: Thank you for your comment and we have added the link for the used data in this manuscript in lines 165 and 502.
Point 7: There are still some unclear expressions and some minor grammatical problems in the work, please correct them carefully.
Response 7: Thank you for your comment. We have modified the manuscript carefully and the modification part is highlighted in red.
Author Response File: 
Author Response.docx
Reviewer 2 Report
It is recommended to incorporate a comprehensive compilation of abbreviations.
The Abstract section of this paper contains excessive information and lacks emphasis on the key results. It is essential to provide specific results rather than a general description in this section.
The present study aims to highlight the original contribution of this work, focusing on its significance in addressing a pertinent scientific issue and addressing a notable research gap or problem.
Emphasise the originality of the research in the concluding section of the introduction.
It is recommended to incorporate quantitative findings within the abstract section.
Suggest potential avenues for future research.
This paper aims to provide a rationale for the selection of the methodology employed in conducting uncertainty analysis.
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Moderate editing of the English language is required.
Author Response
Response to Reviewer 2 Comments
Point 1: It is recommended to incorporate a comprehensive compilation of abbreviations.
Response 1: Thank you for your comment and we have added a symbol table in Appendix A.
Point 2: The Abstract section of this paper contains excessive information and lacks emphasis on the key results. It is essential to provide specific results rather than a general description in this section. The present study aims to highlight the original contribution of this work, focusing on its significance in addressing a pertinent scientific issue and addressing a notable research gap or problem. Emphasize the originality of the research in the concluding section of the introduction. It is recommended to incorporate quantitative findings within the abstract section.
Response 2: Thank you for your comment and suggestions. We have reorganized and condensed the abstract, the introduction, and the reference. Besides, the entire manuscript has been carefully revised and the modification part is highlighted in red.
Point 3: Suggest potential avenues for future research. This paper aims to provide a rationale for the selection of the methodology employed in conducting uncertainty analysis.
Response 3: Thank you for your comment and the related future research has been introduced in Section 4.3. Based on the results of this work, we will further carry out the analysis of the key parameters of the Moon-based non-scanning wide field-of-view radiometer, the construction of the data processing algorithm, and the reduction scheme of the data uncertainty.
Point 4: Moderate editing of the English language is required.
Response 4: Thank you for your comment. We have modified the manuscript carefully and the modification part is highlighted in red.
Author Response File: Author Response.docx
Reviewer 3 Report
Moon-Based Earth Radiation Observation is expected to improve the current Earth radiation budget . The calculation model and its uncerainty of Entrance Pupil Irradiance of different MERO’s instrument is evaluated. This research is very useful to build Moon-based Earth observation system .
Moon-Based Earth Radiation Observation is expected to improve the current Earth radiation budget . The calculation model and its uncerainty of Entrance Pupil Irradiance of different MERO’s instrument is evaluated. This research is very useful to build Moon-based Earth observation system .
Author Response
Response to Reviewer 3 Comments
Comments and Suggestions for Authors:
Point 1: Moon-Based Earth Radiation Observation is expected to improve the current Earth radiation budget. The calculation model and its uncertainty of Entrance Pupil Irradiance of different MERO’s instrument is evaluated. This research is very useful to build a Moon-based Earth observation system.
Response 1: Thank you for your comment.
Comments on the Quality of English Language:
Point 2: Moon-Based Earth Radiation Observation is expected to improve the current Earth radiation budget. The calculation model and its uncertainty of Entrance Pupil Irradiance of different MERO’s instrument is evaluated. This research is very useful to build a Moon-based Earth observation system.
Response 2: Thank you for your comment. We have modified the manuscript carefully and the modification is highlighted in red.
Author Response File: Author Response.docx
Reviewer 4 Report
This paper describes how observations from moon-based platforms can be employed to develop a long time series of Earth;s outgoing longwave and shortwave radiation to complement the existing observations from other Earth radiation budget measurements such as ERBE, CERES, GERB, etc. While such measurements provide unique advantages over the conventional satellite-based observations, authors should cite literature on the planned scientific missions from manned research stations on the surface of the moon, and the timeline for such observations. However the uncertainty analysis is done excellently. I recommend publication after the authors add the requested information.
Author Response
Response to Reviewer 4 Comments
Point 1: This paper describes how observations from moon-based platforms can be employed to develop a long time series of Earth’s outgoing longwave and shortwave radiation to complement the existing observations from other Earth radiation budget measurements such as ERBE, CERES, GERB, etc. While such measurements provide unique advantages over the conventional satellite-based observations, authors should cite literature on the planned scientific missions from manned research stations on the surface of the moon, and the timeline for such observations. However, the uncertainty analysis is done excellently. I recommend publication after the authors add the requested information.
Response 1: Thank you for your comment and we have added the related literature in lines 625-630. In addition, we have reorganized and condensed the abstract, the introduction, and the reference. Besides, the entire manuscript has been revised carefully.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors have addressed most of my comments satisfactorily. The manuscript in its present form is recommended for publication.
Minor editing of the English language is required.
