祁连山夏季两类地形降水过程的环流特征及成因分析  

Analysis of Circulation Characteristics and Causes on Two Types of Topographic Precipitation Processes around the Qilian Mountains in Summer

作　　者：王思懿 隆霄[1,2] 李超 曹怡清 张文煜 WANG Siyi;LONG Xiao;LI Chao;CAO Yiqing;ZHANG Wenyu(College of Atmospheric Sciences,Lanzhou University,Lanzhou 730000,Gansu,China;Key Laboratory of Cloud and Fog Physical Environment,China Meteorological Administration,Beijing 100081,China;School of Earth Science and Technology,Zhengzhou University,Zhengzhou 450001,Henan,China)

机构地区：[1]兰州大学大气科学学院,甘肃兰州730000 [2]中国气象局云雾物理环境重点实验室,北京100081 [3]郑州大学地球科学与技术学院,河南郑州450001

出　　处：《高原气象》2022年第3期593-603,共11页Plateau Meteorology

基　　金：西北区域人工影响天气能力建设项目—研究试验项目(ZQC-R18208);国家自然科学基金项目(41965001,41330527)。

摘　　要：祁连山地区的降水与大尺度环流系统和复杂地形强迫形成的地形云发展变化有关。本文利用多种观测资料对2018年发生在祁连山地区过程降水(2018年7月19-20日,CASE1)和地形云降水(2018年8月28日,CASE2)两类降水过程进行天气学分析,并利用高分辨中尺度数值模式WRFV3.8.1对两类降水过程的数值模拟结果分析了有关物理参量和发展机制等方面的差异。结果表明:CASE1是在有利的大中尺度条件下形成的降水过程,它的形成是大尺度环流系统和局地地形共同作用的结果,CASE2没有明显的大尺度环流系统,主要是由局地地形诱发的降水过程;CASE1具有水汽供给充足,降水发生前大气中层结明显不稳定、对流有效能量大(1064.84 J·kg^(-1))、水平风的垂直切变强(27.6 m·s^(-1))、理查森数(Ri)小于0和垂直上升运动强烈等特点,这有利于产生大范围持续性的降水过程;而CASE2过程中的层结较CASE1的稳定,MCAPE的最大值为546.15 J·kg^(-1),约为CASE1的一半,水平风垂直切变最大值为17.37 m·s^(-1),远小于CASE1的值,理查森数在降水阶段始终大于0,这导致此类降水的降水率相对较小,对流活动较弱,持续时间相对较短。Precipitation around the Qilian Mountains has close relationship with developing of large-scale circulation system and orographic cloud forced by complex topography in this region.The present work compares synoptic pattern and relevant physical parameters as well as development mechanism of two type precipitation processes around the Qilian Mountains such as CASE1 which occurred during July 19-20,2018 and CASE2 which occurred on August 28,2018 with observed data and high resolution data from WRF model version 3.8.1.Synoptic analyses show that CASE1 precipitation process is the result of interaction between favorable large-scale and local topography,CASE2 is mainly a precipitation process induced by local topography and no significant large-scale circulation system in this process.Results of diagnosis analyses indicate that CASE1 has characteristics such as sufficient water vapor supply,obviously unstable of the stratification,high effective convective energy(1064.84 J·kg^(-1)),strong vertical shear of the horizontal wind(27.6 m·s^(-1)),Richardson number(Ri)less than 0 and strong vertical ascending motion et al.before precipitation,which caused the formation of larger area and persistent precipitation process.However,the stratification in CASE2 is more stable than that in CASE1,and the maximum of MCAPE(546.15 J·kg^(-1))is about half of that in CASE1,the maximum horizontal wind vertical shear(17.37 m·s^(-1))is far less than that of CASE1,and Richardson number is greater than 0 in the precipitation stage,which means it is a weak convective precipitation process and precipitation rate is relatively smaller as well as and relatively short duration.

关 键 词：祁连山地区 地形云降水 过程降水 诊断分析 

分 类 号：P435[天文地球—大气科学及气象学]