This study conducted a systematic validation of the aerosol optical depth (AOD) products from the Particulate Observing Scanning Polarimeter (POSP) onboard the Gaofen-5 02 satellite, including comparative analyses with AERONET ground-based observations and MODIS products. The research demonstrates reasonable design, sufficient data volume, rigorous statistical methodology, and scientifically valuable results. It is recommended for acceptance after addressing the following revisions:

1. The specific data quality control procedures for POSP (e.g., cloud detection, outlier removal) remain unclear in the manuscript, potentially affecting result reproducibility. It is recommended to supplement detailed descriptions of POSP data preprocessing steps (e.g., cloud masking, pixel screening criteria) and clarify their impacts on the matching strategy.

2. Line24, Lines 178-182: The significant underestimation in high-AOD regions (e.g., North Africa) is attributed to "aerosol model errors" without specific analysis of discrepancies between model assumptions and actual aerosol characteristics. Further investigation into aerosol model classification and its impact on retrieval errors is suggested.

3. Lines 302-304: The explanation for lower AOD accuracy in urban areas remains overly generalized ("complex surface and diverse pollution components"), lacking quantitative analysis (e.g., interference from urban surface reflectance anisotropy). Enhanced discussion on separating urban surface reflectance from aerosol signals is recommended.

4.Line 246:"Other LC types which are not shown in Fig.4 are presented in Fig. S1." Figs. S1-S9 need to be found in the supplementary document. It is recommended to describe clearly in the manuscript.

5.Some grammatical inconsistencies exist. Comprehensive language polishing is advised to ensure proper tense usage and grammatical consistency throughout the manuscript.

The manuscript presents a global validation of the POSP AOD product using AERONET and MODIS AOD as reference datasets. While the validation is generally sound, the manuscript could be strengthened by addressing the following points:

1) Given that POSP is a new instrument with a novel retrieval algorithm, more detailed information should be provided on the AOD retrieval methodology, particularly regarding the estimation of surface reflectance over land. Since surface reflectance is a critical factor in satellite AOD retrieval, a lack of clarity on how it is treated limits the reader’s ability to understand regional differences in retrieval performance. Clear articulation of the algorithm's treatment of land surface properties would help explain spatial variations in validation results.

2) The manuscript could benefit from being more concise. Since the primary objective is to validate the POSP AOD product, the content should remain focused on presenting the validation methods, metrics, regional analysis, and interpretation of results, minimizing peripheral discussions.

3) The current validation extends a previous preliminary comparison (Nov 2021 – Apr 2022) by covering a longer period (Dec 2021 – Nov 2022). However, the manuscript should clearly articulate the novel contributions of this extended study. For instance, does the longer time series reveal seasonal biases? Are regional patterns more robustly confirmed or refined? Clarifying what new insights are gained will better justify the value of this work.

4) Cloud screening is especially crucial for POSP given its spatial resolution of 6.4 km. However, the current manuscript lacks sufficient details on the cloud masking procedures employed. Please describe how cloud contamination is identified and removed from the observations, and discuss the potential impact of residual cloud effects on the validation results.

5) The reference to Che (2015) is cited in the manuscript but not listed in the References section. Please ensure this citation is properly included and formatted.

6) The citation “Liangfu et al. (2021)” appears to be incorrect. It should be corrected to “Chen et al. (2021)” as per standard citation format.

7) L85-90, Relying on the high-..., it should be polished.