Characteristics and Early Warning Indicators of Polarization Structures in Severe Precipitation Storms over the Southeastern Qinghai Plateau: A Meteorological Analysis

Short-duration heavy rainfall frequently affects the southeastern Qinghai Plateau, but its dual-polarization radar characteristics remain insufficiently documented. This study analyzes ten representative heavy-rainfall convective storms from 2022 to 2025, with the 3 August 2023 Tongren event examined as a representative case. The storms were mainly closely organized deep moist convective systems characterized by a core of vertically integrated liquid water (VIL), high echo tops, a low-centroid mid- to lower-level reflectivity (ZH) column, a shallow low-level differential-reflectivity (ZDR) column, and a specific-differential-phase (KDP) foot. Deep ZDR and KDP columns above the 0 °C level were not observed, and the storm centroid generally remained below half of the echo-top height. During storm evolution, ZHmax, ZDRmax, KDPmax, VILmax, and echo-top height generally increased during development and then fluctuated or decreased during maturity and weakening. High concentrations of small- to medium-sized raindrops were an important contributor to intense plateau rainfall. Based on these structural and temporal characteristics, a four-step multi-parameter nowcasting framework is proposed, with ZHmax and VILmax as primary indicators, KDPmax as a secondary indicator, and echo-top height as a supporting indicator. These results provide an observational basis for short-duration heavy-rainfall nowcasting over complex plateau terrain.