# Retrieval of Cloud Ice Water Path from FY-3F MWTS and MWHS
## 4 Results
### Comparison Between FY-3F Retrieval Results and METOP-C Products  
To validate the accuracy of IWP retrievals from FY-3F satellite data, this study compared them with IWP products derived from METOP-C satellite data. Figure 8 illustrates the global IWP results retrieved from FY-3F and METOP-C satellite data on 24 July 2024. The comparison reveals a high degree of spatial consistency between the two datasets. Additionally, the IWP retrievals from FY-3F data exhibit higher spatial resolution compared to those from METOP-C data, underscoring the significance of FY-3F satellite data for advancing ice cloud research. As illustrated in Figure 10, the IWP retrieval results from FY-3F and METOP-C data demonstrate high spatial consistency. However, significant differences are observed in the Southern Hemisphere, whereas the results in the Northern Hemisphere are nearly identical. Between 30\({}^{\circ}\)N and 60\({}^{\circ}\)N, the mean IWP retrieved using FY-3F data is 0.105 kg/m\({}^{2}\), compared to 0.125 kg/m\({}^{2}\) using METOP-C data. From 30\({}^{\circ}\)N to 30\({}^{\circ}\)S, the mean IWP retrieved from FY-3F data is 0.245 kg/m\({}^{2}\), while that from METOP-C data is 0.234 kg/m\({}^{2}\). Between 30\({}^{\circ}\)S and 60\({}^{\circ}\)S, the mean IWP retrieved using FY-3F data is 0.123 kg/m\({}^{2}\), compared to 0.111 kg/m\({}^{2}\) using METOP-C data. These findings indicate that the IWP retrieval results from both datasets are relatively consistent across different regions. Furthermore, MWTS-III's wider swath compared to MHS enables the FY-3F data to provide better global coverage. This allows for more seamless integration of adjacent scan tracks in mid- to low-latitude regions, significantly enhancing the ability to observe the global distribution of ice clouds. Figure 9: Histogram distribution of differences between IWP retrievals and ERA5 data (1 October 2024): (**a**) oceanic regions, (**b**) land regions, (**c**) oceanic regions with high IWP values (IWP \(>\) 0.1 kg/m\({}^{2}\)), and (**d**) oceanic regions with low IWP values (IWP \(<\) 0.1 kg/m\({}^{2}\)). Figure 11 displays a histogram illustrating the differences in IWP values retrieved from FY-3F and METOP-C data. The histogram exhibits a normal distribution, characterized by a prominent peak near zero and symmetric tails on both sides, indicating a high degree of consistency between the IWP values derived from the two datasets. Most differences fall within the range of \(\pm\)0.25 kg/m\({}^{2}\), which may result from variations in satellite observation angles, differences in data acquisition times, or other factors. To further examine the correlation between IWP values from the two datasets, points with identical locations and scan times were selected to create a correlation scatter plot, shown in Figure 12. The results reveal that IWP values retrieved from FY-3F data are highly correlated with those from METOP-C data, underscoring the accuracy and reliability of the IWP retrieval method using FY-3F data. Figure 13 displays IWP retrieval results for typhoon and extratropical regions based on satellite observational data from 24 July 2024. The IWP retrieved from FY-3F data in the typhoon region shows high consistency with that from METOP-C data and provides higher resolution, enabling a detailed observation of the typhoon's internal structure and path. However, due to its narrower scanning width, the METOP-C data exhibits more missing values, which can affect the analysis of IWP variations. In contrast, FY-3F data mitigates this issue and, with its higher resolution, captures atmospheric ice cloud information more effectively. Figure 10: IWP retrieval results from 24 July 2024: panel (**a**) displays the IWP retrieved using FY-3F observational data, while panel (**b**) presents the IWP product from METOP-C.  
Figure 11: Histogram distributions of differences in IWP retrievals between FY-3F and METOP-C data on 24 July 2024: (**a**) high IWP values (IWP \(>\) 0.1 kg/m\({}^{2}\)), and (**b**) low IWP values (IWP \(<\) 0.1 kg/m\({}^{2}\)).