Characteristics and Applications of Summer Season Raindrop Size Distributions Based on a PARSIVEL2 Disdrometer in the Western Tianshan Mountains (China)

Abstract

The summer season raindrop size distribution (DSD) characteristics and their important applications, based on a PARSIVEL2 disdrometer installed in Zhaosu over the western Tianshan Mountains, China, in 2020–2021 are studied. Our analysis reveals that, for total rainfall and different rainfall types, the DSD in Zhaosu follows the normalized gamma distribution model, and convective rainfall has a higher raindrop concentration than stratiform rainfall at all diameters. For stratiform rainfall, the mean value of mass-weighted mean diameter (Dm) is lower than that of convective DSD, while the mean value of normalized intercept parameter (log10 Nw) is higher than that of convective DSD, and the summer season convective rainfall in Zhaosu is continental convective rainfall according to the conventional classification, which is characterized by relatively larger Dm and lower log10 Nw values. The derived µ–∧ relation in Zhaosu exhibits some differences from those reported in eastern, southern, and northern China and the Tibetan Plateau. Furthermore, derived Z–R relations for stratiform and convective rainfall in Zhaosu are compared with those from other regions. Analysis shows that the empirical relation of Z = 300R1.4 (widely used), strongly overestimates the R of convective precipitation in Zhaosu. The C-band polarimetric radar rainfall estimation relations are derived, and the R(Zh,Zdr) and R(Kdp,Zdr) relations perform the best in quantitative precipitation estimation. Moreover, the empirical Dm–Zku and Dm–Zka relations are derived, which are beneficial to the improvement of rainfall retrieval algorithms of the GPM DPR. Lastly, rainfall kinetic energy relations proposed in this study can be used to better assess rainfall erosivity. The empirical relationships of DSD evaluated in this study provide an opportunity to (1) improve rainfall retrieval algorithms for both ground-based and remote sensing radars and to (2) enhance rainfall kinetic energy estimates in rainfall erosivity studies based on disdrometer and GPM DPR.