西南地区东部夏季降水转化率特征及成因分析  

Characteristics and cause analysis of summer precipitation conversion rate in eastern Southwest China

作　　者：卢楚翰[1,2] 黄丁安 秦育婧 李永华[5] 向波[5] LU Chuhan;HUANG Dingan;QIN Yujing;LI Yonghua;XIANG Bo(Nanjing University of Information Science&Technology,Key Laboratory of Meteorological Disaster of Ministry of Education,Nanjing 210044;Key Laboratory of Ecosystem Carbon Source and Sink,China Meteorological Administration(ECSS-CMA),Wuxi University,Wuxi 214000;Fujian Provincial Key Laboratory of Severe Weather,Fuzhou 350001;Sanming Meteorological Bureau,Sanming 365000;Chongqing Climate Center,Chongqing 401147)

机构地区：[1]南京信息工程大学气象灾害教育部重点实验室,南京210044 [2]无锡学院中国气象局生态系统碳源汇重点开放实验室,无锡214000 [3]福建省灾害天气重点实验室,福州350001 [4]福建省三明市气象局,三明365000 [5]重庆市气候中心,重庆401147

出　　处：《暴雨灾害》2024年第5期499-508,共10页Torrential Rain and Disasters

基　　金：江苏省重点研发计划产业前瞻与关键核心技术项目(BE2022161);中国气象局创新发展专项(CXFZ2022J031);国家自然科学基金项目(41875111)。

摘　　要：利用格点化降水观测数据集(CN05.1)以及ECMWF再分析资料(ERA5),分析1961—2020年夏季西南地区东部(Eastern Southwest China,ESWC)的降水、水汽含量及降水转化率特征,并利用天气学分析方法初步探究地形分布对降水转化率空间分布差异的影响,最后利用中尺度数值模式WRF4.0(Weather Research and Forecasting Model)设计地形敏感性试验验证地形对西南地区东部夏季降水的作用。结果表明:(1)1961—2020年夏季西南地区东部的降水呈现东多西少的分布特征,但水汽含量却在其东南部和西北部存在两个大值区,水汽大值区降水转化率偏低,强降水区与水汽含量大值区分布存在明显差异,通过分析强降水区与水平风场及垂直速度场的形势配合发现地形是导致此差异的重要因素。(2)WRF模式能较好地模拟出西南地区东部夏季降水的空间分布特征,通过地形敏感性试验发现,区域内大娄山、方斗山及大巴山组成的西南-东北向山地地形分布对降水强度有显著影响,地形高度的降低将导致区域东南部降水量显著减少。(3)敏感性试验中将区域地形高度分别降低一半和去除地形后,区域东南部的降水在月时间尺度中将分别减少9.89%和19.90%。地形高度的改变也会引起区域垂直速度、水平风场、水汽输送及水汽辐合量发生改变,当地形高度降低后,上升运动及西南风明显减弱,水汽输送强度降低,水汽辐合量减少,不利于降水形成。Using CN05.1 and ECMWF Reanalysis v5(ERA5)data,the characteristics of precipitation,water vapor content and precipitation conversion rate in eastern Southwest China(ESWC)during the summer of 1961-2020 were analyzed,and the influence of terrain distribution on the spatial distribution difference of precipitation conversion rate was preliminarily explored by means of synoptic analysis.Finally,the mesoscale numerical Weather Research and Forecasting Model(WRF4.0)was used to design terrain sensitivity tests to verify the effect of terrain on summer precipitation in the ESWC.The results are as follow.(1)In the summer of 1961-2020,the precipitation in the ESWC shows the characteristics of more precipitation in the east and less precipitation in the west,but there are two large value areas of water vapor content in the southeast and northwest of ESWC.The precipitation conversion rate in the large value area of water vapor is low,and the distribution of the strong precipitation area and the large value area of water vapor content are significantly different.By analyzing the situation of heavy precipitation areas in conjunction with horizontal wind fields and vertical velocity fields,it is found that topographic distribution is an important factor leading to this difference.(2)WRF model can well reflect the characteristics of summer precipitation in the ESWC.The terrain sensitivity test shows that the southwest to northeast mountain terrain distribution consisting of Dalou Mountain,Fangdou Mountain and Daba Mountain has a significant impact on the intensity of precipitation,and the decrease of terrain height will lead to a significant decrease of precipitation in the southeastern part of the region.(3)In particular,after reducing the topographic height of the region by half and to 0,respectively,the precipitation in the southeast of the region will decrease by 9.89% and 19.90% respectively on the monthly time scale.The change of topographic height will also cause the change of vertical velocity,horizontal wind field,water

关 键 词：西南地区东部 水汽含量 降水转化率 地形敏感性试验 数值模拟 

分 类 号：P426.6[天文地球—大气科学及气象学]