北京地区短时强降水过程的多尺度环流特征  

Multi-scale characteristics of atmospheric circulation related to short-time strong rainfall events in Beijing

作　　者：杨波 孙继松[2] 毛旭 林隐静 YANG Bo SUN Jisong MAO Xu LIN Yinjing(National Meteorological Center, Beijing 100081, China Beijing Meteorological Observatory ,Beijing 100081, China)

机构地区：[1]国家气象中心,北京100081 [2]北京市气象台,北京100089

出　　处：《气象学报》2016年第6期919-934,共16页Acta Meteorologica Sinica

基　　金：公益性行业(气象)科研项目(GYHY201506006);国家科技支撑计划(2015BAC03B04);国家自然科学基金项目(41475051)

摘　　要：为了探讨不同天气尺度背景下,北京地区短时强降水过程的基本特征,利用2007—2014年6—8月北京地区自动气象站观测数据和ECMWF ERA-Interim(0.5°×0.5°)全球再分析数据,在对北京地区短时强降水日的大尺度环流特征进行分型的基础上,基于分型合成场和距平场分析了北京地区短时强降水天气过程的基本环流背景及相应的中尺度环流特征。结果表明:(1)造成北京地区出现短时强降水过程的天气系统,依据其出现的频次,大体可分为副热带高压(副高)与西来槽相互作用型、西风小槽型、东北冷涡型和黄淮低涡倒槽型等4类;从低层水汽来看,除东北冷涡型主要来自于渤海、黄海外,其他3型短时强降水过程的水汽主要来自中国南海或东海。(2)不同天气系统主导下的短时强降水时空分布存在较大差异:在空间分布上,黄淮低涡倒槽型短时强降水带分布从北京东南平原穿过城区至西北山前成东南—西北走向,其余3型大体上沿北京地形成西南—东北走向,其中,西南山前、城区和东北山前地区是3个短时强降水事件的多发中心;在时间分布上,东北低涡型造成的短时强降水过程主要发生在午后,副高与西来槽相互作用型主要集中在傍晚至前半夜,而西风小槽型和黄淮低涡倒槽型短时强降水表现出较强的夜雨特征。(3)从中尺度环流特征上看,副高与西来槽相互作用型短时强降水过程主要是低层冷空气从北京西部、北部进入,首先触发山区对流,与之对应的雷暴高压逐渐组织化,外侧辐散气流(冷池出流)和山前的偏南风暖湿气流辐合造成对流过程加强;西风小槽型主要是边界层内较强东南风在北京西北部山前受地形阻挡,向两边绕流,西南支气流在西部形成气旋性环流,造成城区西部的对流性天气,东北支气流在东北部山前形成地形辐合线,夜间随着东南气流中偏南分量显著加强,东北部山�Auto-weather station observations and ERA-Interim reanalysis data are used to investigate large and meso-scale circulation characteristics related to short term heavy rainfall events over Beijing during June to August from 2007 to 2014.This is done by classifying large-scale synoptic circulations.The results show that：（1）according to their occurrence frequencies,weather systems generally are able to be classified into four synoptic types for short term heavy rainfall events,i.e.the interaction between subtropical high and western trough（Ⅰ）,small trough moving along the westerly stream（Ⅱ）,cold vortex in northeastern China（Ⅲ）,and low-pressure vortex or inverted trough over Huanghuai Plain（Ⅳ）.Except that water vapor comes from Bohai Sea and Yellow Sea for TypeⅢ,for the other three patterns the water vapor are related to remote supplies from the South China Sea and the East China Sea;（2）temporal and spatial distributions of short-time strong rainfall are different with different weather systems：the rainfall distribution is along the southeast-to-northwest mountain range extending from the southeastern plain across the urban area to northwestern mountains under TypeⅣ.However,the rainfall distribution under the other three types is generally along the southwest-to-northeast mountain range（also along the topography in Beijing area）.In particular,three high frequency centers are located in front of at the southwestern and northeastern mountains and central urban area respectively.Looking at the time series,it is found that short-time strong rainfall mainly occurs in the afternoon for TypeⅢ,from dusk till mid-night for TypeⅠ,and at night for TypeⅡ andⅣ;（3）looking at the meso-scale characteristics,convections over mountainous area in Beijing are often triggered first by cold air at the lower level in western and northern Beijing,followed by organized thunderstorm highs.The cold pool outflow from the thunderstorm high and the warm moist airflow from the southerly winds

关 键 词：短时强降水 天气分型 中尺度环流特征 地形 

分 类 号：P458.121[天文地球—大气科学及气象学]