Microphysical Characteristics of Rainfall Based on Long-Term Observations with a 2DVD in Yangbajain, Tibet

Abstract

Raindrop size distribution (DSD) plays a crucial role in enhancing the accuracy of radar quantitative precipitation estimates in the Tibetan Plateau (TP). However, there is a notable scarcity of long-term, high-resolution observations in this region. To address this issue, long-term observations from a two-dimensional video disdrometer (2DVD) were leveraged to refine the radar and satellite-based algorithms for quantifying precipitation in the hinterland of the TP. It was observed that weak precipitation (R<1, mm h⁻¹) accounts for 86% of the total precipitation time, while small raindrops (D<2 mm) comprise 99% of the total raindrop count. Furthermore, the average spectral width of the DSD increases with increasing rain rate. The DSD characteristics of convective and stratiform precipitation were discussed across five different rain rates, revealing that convective precipitation in Yangbajain (YBJ) exhibits characteristics similar to maritime-like precipitation. The constrained relationships between the slope Λ and shape μ, D_m and N_w of gamma DSDs were derived. Additionally, we established a correlation between the equivalent diameter and drop axis ratio and found that raindrops on the TP attain a nearly spherical shape. Consequently, the application of the rainfall retrieval algorithms of the dual-frequency precipitation radar in the TP is improved based on the statistical results of the DSD.