摘要
采用FY-2E卫星云图TBB(Black Body Temperature)资料,统计分析2010-2014年夏季(6-8月)华东地区的α中尺度对流系统(MαCS)和β中尺度对流系统(MβCS),发现两类MCS(Mesoscale Convective System)均具有夜发性,且发生主要集中于安徽、江苏、江西和浙江地区,形成后自西向东移动。进一步利用NCEP-CFSR和NCEP-CFSV2每6 h的再分析数据,通过主成分分析(Principal Component Analysis,PCA)和K-means聚类分析对两种尺度MCS成因进行分析,结果显示:850 hPa切变线和低空急流、500 hPa副高和中纬度短波槽以及200 hPa的高空急流是影响MCS形成主要的天气系统,对流层中层以下的水汽供应、低层大气不稳定性和低层辐合、高层辐散的动力结构是MCS形成的必要条件。MαCS发生前的天气形势可以分为两类:①生成位置位于850 hPa低空急流的西侧、气旋性环流的南侧,500 hPa、200 hPa分别受槽前西南气流、反气旋性环流的影响;②850 hPa切变线南部的偏西气流、500 hPa的偏西气流和200 hPa的高空急流配合。MβCS发生前的两类环流形势中,850 hPa切变线南部的偏西气流控制的为第一类,切变线南部的西南气流和生成位置东部的低空急流影响的为第二类,500 hPa生成位置位于短波槽东部,200 hPa均有西风急流与中低层配合。
By using TBB( Black Body Temperature) data of FY-2 E satellite,statistical research of Meso-α Convective System( MαCS) and Meso-β Convective System( MβCS) occurred over East China in summer( from June to August) during the year of 2010 to 2014 is carried out respectively,which finds two scales of MCS are nocturnal that mainly occurred in Anhui,Jiangsu,Jiangxi and Zhejiang area and moved from west to the east.Based on the reanalysis data of NCEP-CFSR and NCEP-CFSV2 every 6 hours,the causes of MCS were analyzed by principal component analysis( PCA) and K-means clustering analysis.Secondly,the analysis of the formation cause of two kinds of MCS shows the shear line and low-level jet at 850 hPa,subtropical high and short wave trough in middle latitude at 500 hPa and upper-level jet at 200 hPa are the main impact systems before MCS formed.The water vapor supply in the middle and lower troposphere,atmospheric instability in the lowlayer and the power structure of convergence at lowlevel and divergence at upper level are the necessary conditions for the formation of MCS.The weather situation before initiation of MαCS can be divided into two categories:( 1) the formation position is in the western part of the lowlevel jet and the southern part of the cyclonic circulation at 850 h Pa,and affected respectively by the southwest airflowin front of trough at 500 h Pa and anti-cyclonic circulation at 200 h Pa;( 2) westerly flowin the south of the shear line at 850 hPa and westerly flowat 500 hPa cooperated with the upper-level jet at 200 hPa.In the two types of circulation situations before the occurrence of MβCS,the westerly in the southern part of the shear line at 850 hPa controls is the first type,while the southwest flowin the southern part of the shear line and lowlevel jet in east of the formation position belongs to the second category. Both of them correspond to short wave trough in the eastern part of the formation position at 500 hPa and westerly jet at200 h Pa.
作者
张柳
霍利微
潘玉洁
ZHANG Liu;HUO Liwei;PAN Yujie(Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD),Nanjing University of Information Science&Technology,Nanjing 210044,China)
出处
《大气科学学报》
CSCD
北大核心
2020年第2期392-404,共13页
Transactions of Atmospheric Sciences
基金
国家重点研发计划资助项目(2019YFC1510201)
国家自然科学基金资助项目(41905061
91437104)。
关键词
华东地区
中尺度对流
系统
主成分分析
聚类分析
East China
MCS
activity characteristics
principal component analysis
cluster analysis
