## 4 Results
### Model Performance in Typical Rainfall Events
#### 4.3.2 Comparison of the Spatial Distribution  
During the testing stage, two rainfall events of different magnitudes were selected, and their cumulative rainfall spatial distributions were plotted. The resulting figures (Figures 8 and 9) show the distribution of GPM, F-SVD, and FS-ConvLSTM from left to right.  
Figure 8: Spatial distribution of the accumulated precipitation for small and moderate rainfall events. (**a**) Small rain; (**b**) Moderate rain.  
As seen in Figure 8a, the rainfall epoch for light rainfall events is around 3 days. The values of F-SVD and FS-ConvLSTM are closer, while the magnitude of the GPM data is significantly larger. For spatial extreme values of accumulated rainfall, the minimal values of FS-ConvLSTM and the minimal values of GPM are closer, and the maximal values of FS-ConvLSTM are slightly larger than those of F-SVD. GPM and FS-ConvLSTM are more continuous in spatial variation, while F-SVD has multiple isolated points in space that can produce abrupt changes in rainfall amounts. The rainfall centers of GPM and F-SVD are slightly different in space, and the rainfall centers of the two data and the rainfall distribution of the surrounding points are reflected in the fusion data. Similar results are found for the medium rainfall event, as seen in Figure 8b, where the duration of the medium rainfall event is around two days. The magnitude of GPM estimation is higher than the other two data, and the spatial extremes of F-SVD and FS-ConvLSTM are very close. The spatial distributions of the three data are relatively similar, but the values for F-SVD are more discrete in terms of spatial variation compared to the continuous spatial variation of GPM and FS-ConvLSTM. The fused data combine the distribution characteristics of GPM and F-SVD, with the spatial aggregation of rainfall of both reflected in the fusion.  
For heavy rainfall events, as depicted in Figure 9a, the rainfall duration lasts for approximately four days. GPM continues to overestimate the rainfall magnitude, while the magnitudes of F-SVD and FS-ConvLSTM are closer and the spatial extremes are similar. The spatial distribution of rainfall reflected by GPM and F-SVD are similar, and the location of the rainfall center is also close, corresponding to a similar distribution in the fused data. FS-ConvLSTM shows better spatial continuity. As for the torrential rainfall events, as shown in Figure 9b, the rainfall duration lasts for approximately four days. GPM continues to overestimate the rainfall magnitude, while the magnitudes of F-SVD and FS-ConvLSTM are closer and the spatial extremes are similar. The spatial distribution of rainfall reflected by GPM and F-SVD are similar, and the location of the rainfall center is also close, corresponding to a similar distribution in the fused  
in Figure 8(b), the rainfall duration is about 3-4 days. Regarding rainfall magnitude, GPM is relatively large compared to the other two types of data. In terms of spatial distribution, F-SVD shows abrupt changes, and the rainfall at a few points is significantly higher than at other surrounding points, resulting in poor spatial continuity. Moreover, GPM and F-SVD have single and multiple rainfall centers, respectively, and the distribution of both rainfall centers is reflected in the fusion.  
In general, GPM exhibits continuous spatial distribution but overestimates rainfall events. F-SVD shows abrupt spatial variations but is more accurate in its response to magnitude. FS-ConvLSTM combines the advantages of GPM in spatial distribution and the advantages of F-SVD in magnitude, which display continuous spatial distribution and closely approximate the actual rainfall values.