邵阳一次极端暴雨过程成因分析

Analysis of the Causes of an Extreme Rainstorm Event in Shaoyang

摘要: 利用常规观测资料及ERA5再分析资料，对2025年6月7~8日邵阳极端暴雨过程的环流背景与物理量特征进行诊断分析。结果表明：过程具有强对流性和局地极端性，环流分析显示，200 hPa高空急流出口区右侧分流辐散提供强烈抽吸作用，地面暖低压倒槽稳定维持，低层冷空气是极端暴雨的触发机制。热力场上，对流发生前大气呈高能高湿状态，暖云层深厚；动力场上，中层为较强上升运动和辐合中心；南海、孟加拉湾–北部湾暖湿气流是暴雨的水汽源，湘西南一带配合有较强水汽辐合中心。低层风场脉动及低层冷空气渗透是本次极端暴雨预报预警中有不容忽视的重要因素。对流云团位置与强降水落区有较好对应关系，强降雨中心出现在TBB低值中心附近或低值到高值梯度较大处。

Abstract: Conventional observation data and ERA5 reanalysis data are used to conduct a diagnostic analysis of the circulation background and physical quantity characteristics of an extreme rainstorm event in Shaoyang from June 7 to 8, 2025. The results indicate that the process exhibited strong convectivity and local extremity. Circulation analysis revealed that the right-side divergence of the 200 hPa upper-level jet stream outlet provided a strong suction effect, a stable maintenance of the surface warm low-pressure inverted trough, the low-level cold air served as the triggering mechanism for the extreme rainstorm. In the thermal field, the atmosphere was in a high-energy and high-humidity state before convection occurred, with deep warm clouds; Dynamically, the mid-level features strong upward motion and a convergence center. The warm and moist airflows from the South China Sea and the Bay of Bengal-Beibu Gulf were the water vapor sources for the rainstorm, accompanied by a strong water vapor convergence center in southwestern Hunan Low-level wind field fluctuations and the infiltration of low-level cold air were important factors that could not be ignored in the forecast and early warning of this extreme rainstorm. The convective cloud clusters corresponded well with the heavy precipitation area, and the heavy rainfall center appears near the low TBB center or in areas with a large gradient from low to high TBB values.