四川盆地西部边缘不同落区暴雨的气象场差异及夜雨浅析  

Analysis of Meteorological Fields and Nighttime Rainfall Mechanism in Different Precipitation Areas on the Western Fringes of Sichuan Basin

作　　者：杨康权[3,4] 卢萍 YANG Kangquan;LU Ping(State Key Laboratory of Severe Weather,Chinese Academy of Meteorological Sciences,Beijing 100081;Institute of Plateau Meteorology,China Meteorological Administration(CMA),Chengdu 610072;Sichuan Meteorological Observatory,Chengdu 610072;Heavy Rain and Drought–Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072)

机构地区：[1]中国气象科学研究院灾害天气国家重点实验室,北京100081 [2]中国气象局成都高原气象研究所,成都610072 [3]四川省气象台,成都610072 [4]高原与盆地暴雨旱涝灾害四川省重点实验室,成都610072

出　　处：《大气科学》2024年第5期1783-1795,共13页Chinese Journal of Atmospheric Sciences

基　　金：四川省自然科学基金项目2022NSFSC0021;科技部国家重点研发计划2022YFC3003902;灾害天气国家重点实验室开放课题项目2021LASW-A06。

摘　　要：本文基于2015~2018年四川盆地西部边缘出现的典型暴雨个例,以落区为依据进行了统计分类,着重分析了不同空间分布特征暴雨的环境场条件,并从四川盆地夏季大气日变化特征角度来探讨了该区域夜雨频发的原因。研究表明:(1)受四川盆地西部边缘高大陡峭地形影响,盆地西部中低层大气温湿条件好,暖湿东南气流在此遇大地形产生迎风辐合抬升,易发生强降水。当暴雨发生在整个盆西(西部型)时,整个盆地西部的湿度非常大,东南风较强;当暴雨发生在盆地西北部(西北型)时,中低层东南风最强,动力作用最显著;当暴雨发生在盆地西南部(西南型)时,大多伴随有偏北风进入盆地,存在明显的南北风切变辐合。水汽散度通量对四川盆地西部暴雨强度和落区具有较好的指示意义。(2)对流有效位能、相对湿度、假相当位温、中低层风场以及散度这些热力和动力变量的日变化特征,都表明了四川盆地西部降水易发生在夜间。This study examines typical rainstorms on the western fringes of the Sichuan Basin from 2015 to 2018.The environmental field conditions associated with these rainstorms and their spatial distribution characteristics were also analyzed.Furthermore,it investigates the reasons behind the frequent occurrence of nighttime rainfall in the Sichuan Basin based on the atmospheric diurnal variation characteristics during summer.The results are as following:(1)The high and steep terrain of the Sichuan Basin’s western margin affects air temperature and humidity in the middle and lower layers of the western basin.This area is characterized by warm and humid southeast airflow that converges and lifts upon encountering large terrain,resulting in heavy rainfall.When rainstorms occur across the basin’s western region(referred to as west type),the humidity in the entire western basin is exceptionally high,accompanied by a strong southeast wind.When these storms occur in the basin’s northwestern region(the northwest type),the southeast wind at the middle and low levels is at its strongest,creating the most significant dynamic effect.However,rainstorms in the basin’s southwestern region(the southwest type)are usually accompanied by northerly wind entering the basin,resulting in noticeable north–south wind shear convergence.The water vapor divergence flux serves as a good indicator of the intensity and location of heavy rain in the western Sichuan Basin.(2)The diurnal variations of several factors,including the convective available potential energy,relative humidity,pseudo-equivalent potential temperature,and wind field at low and middle levels,indicate the tendency for precipitation to occur at night in the western Sichuan Basin.

关 键 词：四川盆地 暴雨落区 夜雨 日变化 

分 类 号：P447[天文地球—大气科学及气象学]