白鹤滩水电站干热河谷区2018—2021年湿季暴雨大风的环流形势特征研究
Circulation Characteristics of Wet Season Rainstorm and Gale in the Dry-Hot River Valley of Baihetan Hydropower Station
中文摘要：
白鹤滩水电站位于金沙江下游的干热河谷区，大风天气频发，且湿季经常伴随强降雨的发生。为了探究该特殊地形下湿季暴雨大风发生时大气环流及低空急流的演变特征，利用地面观测资料和ERA5再分析资料，分析了2018—2021年白鹤滩坝区湿季13次暴雨大风事件的形成机理。结果表明：1）依据500 hPa环流形势特征可将该地区13次暴雨大风过程分为低槽东移型、副热带高压型、低槽和副热带高压共同影响型，以及热带低压型。2）4类暴雨大风过程700 hPa均伴随显著的低空急流发展，表现为受夏季风影响的西南风急流呈现出东移减弱的趋势，副热带高压西北侧的偏西风急流和偏东南风急流，以及孟加拉湾地区热带低压北侧的偏南风急流，在暴雨过程中起到水汽输送的作用。3）根据暴雨大风的关键影响系统和低空急流演变，建立白鹤滩水电站坝区4类暴雨大风的概念模型。暴雨大风主要受西风槽东移的影响，以及在副热带高压边缘和热带低压北侧充沛水汽输送的条件下发生，低空急流对暴雨大风的触发与维持起到重要作用。
中文关键词：
白鹤滩水电站，暴雨大风，环流形势，低空急流，概念模型
KeyWords：
Baihetan Hydropower Station (BHS), rainstorm and gale, circulation situation, low-level jet, conceptual model
Abstract：
The Baihetan Hydropower Station (BHS) is located in the dry-hot river valley downstream of the Jinsha River, where frequent windy weather and rainstorm during the wet season are common. In order to explore the characteristics of the evolution of atmospheric circulation and low-level jet during wet season rainstorm and gale events in this particular terrain, ground observation data and ERA5 reanalysis data are used to analyze the formation mechanism of 13 wet season rainstorm and gale events in the dam area of BHS from 2018 to 2021. The results show that based on the characteristics of the 500 hPa circulation pattern, the 13 rainstorm and gale events can be classified into 4 types: eastward-moving low trough type, subtropical high type, joint influence of low trough and subtropical high type, and tropical depression type. In all 4 types of rainstorm and gale events, there is always a significant development of low-level jets at 700 hPa, characterized by the weakening and eastward movement of the southwest jet stream due to the influence by the summer monsoon. The westward jet stream and the southeastward jet stream on the northwest side of the subtropical high as well as the southward jet stream on the northern side of the tropical depression in the Bay of Bengal are responsible for water vapor transport during rainstorm events. Based on the key influencing systems and low-level jet evolution, conceptual models of the 4 types of rainstorm and gale events in the dam area of BHS are established. The occurrence of the 4 types of rainstorm and gale events is mainly influenced by the eastward movement of the westerly trough, as well as favorable conditions of abundant water vapor transport on the edge of the subtropical high and the northern side of the tropical depression. Lowlevel jets play an important role in triggering and maintaining rainstorm and gale.