四川盆地西部一次暖区山地暴雨事件的动力过程分析与局地环流数值模拟  

Dynamic Analysis and Local Circulation Numerical Simulation of a Warm-sector Mountain Rainstorm Event in the Western Sichuan Basin

作　　者：付智龙 李国平[1,2] 姜凤友 郭洁 FU Zhilong;LI Guoping;JIANG Fengyou;GUO Jie(School of Atmospheric Sciences,Chengdu University of Information Technology,Chengdu 610225;Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters,Nanjing University of Information Science&Technology,Nanjing 210044;Hulunbuir Meteorological Bureau of Inner Mongolia Autonomous Region,Hulunbuir 021008;Institute of Plateau Meteorology,China Meteorological Administration(CMA)/Heavy Rain and Drought–Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072)

机构地区：[1]成都信息工程大学大气科学学院,成都610225 [2]南京信息工程大学气象灾害预报预警与评估省部共建协同创新中心,南京210044 [3]内蒙古呼伦贝尔市气象局,呼伦贝尔021008 [4]中国气象局成都高原气象研究所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》2022年第6期1366-1380,共15页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金项目42175002、91937301、42075013;国家重点研发计划项目2018YFC1507200。

摘　　要：本文利用国家基本站和区域自动站逐小时雨量、FY-2G卫星TBB、ERA5再分析等资料,对2017年7月23日发生在四川盆地西部的一次暖区山地暴雨事件进行动力诊断分析和数值模拟试验。主要得到以下结果:(1)此次暖区山地突发性暴雨发生在西太平洋副热带高压边缘的弱天气形势背景下,盆地西部前期高温、高能的环境条件与伸入盆地的东南风受到龙门山脉的强迫抬升是这次暴雨触发的诱因。(2)山地—平原环流在夜间的转换使背景东南风形成深厚的倾斜上升运动,是暴雨增强和中尺度对流云团重组发展的原因。(3)进一步通过数值模拟得出,山地—平原环流受近地面热力扰动驱动。在白天,盆地西部山坡为正虚温扰动区,而同一高度的平原则是负虚温扰动,山地—平原环流从平原吹向山地;到了夜晚,虚温扰动在山地、平原两侧的分布发生反转,山地—平原环流因此转为从山地吹向平原;当去除模式地面热源时,近地面的热力扰动几乎消失,盆地西部山地—平原环流无法形成,与山地—平原环流对应的辐合区随之消失,导致模拟的过程累积降水量显著减少、强降水中心消失。Based on the hourly precipitation data from automatic weather stations,FY-2G TBB data,and ERA5 reanalysis data,dynamic analysis and numerical experiments are performed for a warm-sector mountain rainstorm event in the western Sichuan Basin on 23 July 2017.The results showed that:(1)The warm-sector mountain torrential rainstorm occurred at the edge of the West Pacific subtropical high under the background of weak synoptic forcing.The high temperature and high energy in the western Sichuan Basin and the southeast wind intruding into the basin,lifted by Longmen Mountain,induced this rainstorm.(2)The conversion of the mountain-plain circulation is the reason for the intensification of the rainstorm and the reorganization of the mesoscale convective cloud clusters.(3)Moreover,the mountain-plain circulation uplifts the background wind that causes the upward sloping motion.Further study of the results of the numerical simulation showed that the mountain-plain circulation is driven by near-surface thermal perturbation.In the daytime,a positive virtual temperature disturbance area on the hillside of the western Sichuan Basin is detected,and a plain-to-mountain flow is developed.After sunset,the distribution of the virtual temperature disturbance on the mountain and plain is reversed.Therefore,the mountain-plain circulation shifts from mountain to plain.When the model surface heat source is removed,the near-surface thermal perturbation tends to disappear,and the mountain-plain circulation does not form in the western Sichuan Basin.Consequently,the convergence area related to the mountain-plain circulation dissipates,resulting in the decline of the simulated cumulative precipitation and the disappearance of the heavy precipitation center.

关 键 词：暖区山地暴雨 山地—平原环流 昼夜转换 地面热源 数值模拟 

分 类 号：P458[天文地球—大气科学及气象学]