# Studies of General Precipitation Features with TRMM PR Data: An Extensive Overview
## 6 Conclusions and Prospects
### The Next-Generation Space-Borne Precipitation Radar  
The weakness of PR observations can be overcome or partly overcome by the implementation of Global Precipitation Measurement (GPM) mission [167; 168; 169]. The GPM series of satellites take over TRMM satellite to observe the global rainfall. The Core Observatory satellite of GPM series was launched in late February, 2014 and it flies at an altitude of 407 kilometers in a non-Sun-synchronous orbit with an inclination 65\({}^{\circ}\), covering most of the Earth's surface except the polar regions. The Core Observatory carries a Dual-frequency Precipitation Radar (DPR) with a minimum detectable reflectivity of 12 dBZ and a GPM Microwave Imager (GMI) with 13 channels (Figure 9) [170]. The DPR consists of a Ku-band precipitation radar (KuPR, 13.6 GHz) and a Ka-band precipitation radar (KaPR, 35.5 GHz). The swath width is 245 km for KuPR and is 120 km for KaPR. The horizontal spatial resolution at the nadir is 5 km for both radars while the range resolution is 250 m for KuPR and 250/500 m for KaPR. The two radars detect rainfall from different views, which can give more accurate rainfall information and improve the ability to look at raindrop characteristics by using the differential observation between KuPR and KaPR. DPR can provide more accurate rain rate estimates, which in turn can be used to adjust the rain rate estimates of GMI onboard GPM Core and passive microwave (PMW) instruments onboard other satellites in the GPM constellation. Together with GMI, the size distribution of precipitation particles can be acquired and thus the accuracy of rainfall estimation can be improved. As a result, DPR can provide measurements of more accurate, extended coverage, and dynamic range. Compared with TRMM PR, the higher detection capability of GPM DPR will make an even greater contribution to scientific research and social service. There are many global meteorological targets that can be explored with the DPR observation, e.g., precipitation features in mid- and high-latitudes including light rain and snow, the global water cycle and related climate change, climate system variability and climate diagnostics, and data assimilation for numerical models.  
Most recently, version 8 of TRMM PR products came out [171]. The new version of PR data is an improvement compared with the older versions and is compatible with GPM DPR products, which ensures that the space-borne radar has a consistent data suite of more than 20 years. The putting into use of the new generation space-borne radar and the new version data will bring new discoveries in future.  
**Author Contributions:** [PERSON] summarized the general precipitation features from the existing studies and wrote the manuscript; [PERSON] provided the idea of this review study; [PERSON] consulted some of the literature; [PERSON] offered some suggestions and polished the manuscript.  
**Funding:** This research was funded by the National Natural Science Fundation of China (Grant No. 41675028), China Commonwealth Industry Research Project (Grant No. GYHY201306078), the National Key R&D Program on Monitoring, Early Warning and Prevention of Major Natural Disasters (Grant No. 2017 YFC1501401), and U.S. Department of Health and Human Services (Grant No. H49 MC00068).  
**Acknowledgments:** The authors appreciate Professor [PERSON] for his editing.  
**Conflicts of Interest:** The authors declare no conflict of interest.