**5. Conclusions**

The Sichuan Basin and its surrounding areas are divided into three types of terrain based on ETOPO1, including plains, mountains, and high mountains. The Ze and the vertical structural of SP and CP particles over the three types of terrain were analyzed by measurements and retrievals from GPM DPR from May to September of 2014–2021. The major conclusions of this study can be summarized as follows.


grow rapidly, and thus it is easier to form larger raindrops. For heavy precipitation, the higher the elevation, the larger the Dm above 10 km altitude.


The present study mainly focuses on heavy rain DSD, by comparing the DSD characteristics at low-altitude flat terrain and high-altitude complex terrain, leads to evidence and understanding about the effect of Sichuan's unique orography on rain physics. It is very clear from the present study that for heavy precipitation, high-altitude complex terrain has a higher occurrence probability of larger raindrops than plains in Sichuan. This situation is critical because larger rain drops could cause more soil erosion, which leads to the triggering of landslides [26]. Therefore, in the present study on the orographic effect of rain DSD, it would also be useful and throw more light on landslide triggering mechanisms. Likewise, preliminary connections between some physical quantities would help improve the current understanding of the effects of Sichuan's unique topography on microphysical precipitation processes. The current work is a preliminary study focusing on some facts about the characteristics and differences due to different terrains, as well as the internal relationships and mechanisms that remain to be studied further in the future.

**Author Contributions:** Conceptualization, C.S. and G.L.; methodology, C.S. and G.L.; software, C.S.; validation, C.S. and G.L.; formal analysis, C.S.; investigation, C.S.; resources, G.L.; data curation, C.S.; writing—original draft preparation, Y.D. and G.L.; writing—review and editing, G.L.; visualization, C.S.; supervision, G.L.; project administration, G.L.; funding acquisition, G.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Natural Science Foundation of China, gran<sup>t</sup> No. 42175002, No. 91937301, No. 42075013.

**Data Availability Statement:** 2A.DPR V06 dataset is publicly available. The dataset can be found here: https://storm.pps.eosdis.nasa.gov/storm/ (accessed on 5 February 2022).

**Acknowledgments:** The authors sincerely thank the reviewers for their constructive comments and editorial suggestions, which have greatly contributed to the quality of the paper.

**Conflicts of Interest:** The authors declare no conflict of interest.
