Comparison of summer raindrop size distribution characteristics in the western and central Tianshan Mountains of China

The microphysical processes of cloud and precipitation in the Tianshan Mountains still remain unclear due to the complex terrain and the lack of ground-based observational data. In this study, the characteristics of summer raindrop size distribution (RSD) in the western and central Tianshan Mountains of China were investigated in 2020 and 2021. According to the average raindrop spectra, the RSD characteristics exhibit significant differences that the concentration of medium and large particles is relatively higher at Zhaosu than that at Tianchi. Weak precipitation prevails in the Tianshan Mountains most of the time, yet moderate rainfall and heavy rainfall have a great impact on the accumulated rainfall amount. For each rainfall rate class, raindrops of diameter less than 0.75mm have a lower concentration and raindrops of diameter greater than 3 mm have a higher concentration at Zhaosu as compared to those at Tianchi. Compared with Tianchi, Zhaosu has a larger mass-weighted mean diameter (D-m) and a lower normalized intercept parameter (log(10)N(w)). Compared with the classical convective spectrum, the RSDs at both Zhaosu and Tianchi are similar to the continental convective cluster. The relationships between the shape and slope (mu-?), and radar reflectivity and rainfall rate (Z-R) exhibit a significant difference in the western and central Tianshan Mountains of China.