# Retrieval of Cloud Ice Water Path from FY-3F MWTS and MWHS
## 5 Conclusions and Discussion  
To accurately retrieve IWP and obtain high-resolution retrieval results, this study utilized observational data from MWTS-III and MWHS-II onboard the FY-3F satellite. A physical retrieval algorithm was applied to derive IWP values, which were then compared with the ERA5 reanalysis product and METOP-C data. Analysis of probability density distribution plots and cumulative distribution function curves revealed that the IWP retrieved using FY-3F data exhibited numerical distribution characteristics consistent with ERA5, with a generally similar global distribution. Comparisons between satellite products and reanalysis data on both global and regional scales showed that FY-3F and METOP-C retrievals achieved higher resolution than ERA5, enabling clearer observations of IWP magnitude and density distribution--an important advancement for IWP research. In cyclonic regions, FY-3F retrievals effectively captured the internal structure and movement paths of typhoons, significantly aiding continuous observation and predictive analysis. Long-term variation analysis showed that FY-3F IWP retrievals aligned closely with ERA5 data while better capturing seasonal variation characteristics, enhancing their utility for studying IWP relationships with other atmospheric variables. A comparison of difference histograms and scatter plots between FY-3F and METOP-C products revealed a high correlation, indicating that FY-3F retrievals not only showed strong consistency with reanalysis data but also high alignment with other satellite observations. Latitude-based comparisons further confirmed the spatial and numerical consistency of FY-3F retrievals with METOP-C data. Separate statistical analyses for oceanic and land regions demonstrated the high accuracy and global applicability of FY-3F IWP retrievals. However, due to the cross-track scanning nature of microwave sounders, pixel resolution varies significantly between nadir and scan edges, introducing inconsistencies in IWP representation. Given the large spatial variability of IWP, it is critical to account for the effects of resolution variations when using these products. Additionally, since ERA5 data are not absolute truth values, further validation of IWP retrieval accuracy is necessary. Future studies should integrate data from multiple satellites to enhance validation and refine retrieval accuracy. Figure 15: Distribution of IWP across latitude bands, based on FY-3F and METOP-C satellite data from June to July 2024. **Author Contributions:** Conceptualization, F.W. ; methodology, F.W. ; software, F.C. ; validation, F.C., H.H., C.D., X.F. and J.Y. ; formal analysis, F.C. ; investigation, F.C. ; resources, H.H. ; data curation, F.C. ; writing--original draft preparation, F.C. ; writing--review and editing, H.H. ; visualization, F.C. ; supervision, F.W. ; project administration, F.W. ; funding acquisition, F.W. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the National Key R&D Program of China (grant no. 2024 YFB3908300), the National Natural Science Foundation of China (U2142212, 42475165), and the Hunan Provincial Natural Science Foundation of China (grant no. 2021 JC0009), and the Fengyun Application Pioneering Project (FY APP). **Data Availability Statement:** The FY-3F data can be downloaded from the website: [[https://satellite.nsmc.org.cn/PortalSite/Data/Satellite.aspx](https://satellite.nsmc.org.cn/PortalSite/Data/Satellite.aspx)]([https://satellite.nsmc.org.cn/PortalSite/Data/Satellite.aspx](https://satellite.nsmc.org.cn/PortalSite/Data/Satellite.aspx)) (accessed on 21 March 2025). The METOP-C data can be downloaded from the website of the NOAA Comprehensive Large Array-data Stewardship System (CLASS): [[https://www.aev.class.noaa.gov/saa/products/welcome](https://www.aev.class.noaa.gov/saa/products/welcome)]([https://www.aev.class.noaa.gov/saa/products/welcome](https://www.aev.class.noaa.gov/saa/products/welcome)) (accessed on 25 March 2025).