西太平洋副热带高压西伸过程的合成特征及其可能机理  

THE COMPOSITE FEATURES AND POSSIBLE MECHANISMS DURING THE WESTWARD EXTENSION OF SUBTROPICAL HIGH IN THE WESTERN PACIFIC

作　　者：罗玲[1] 何金海[1] 谭言科[2] 

机构地区：[1]南京信息工程大学,南京210044 [2]解放军理工大学气象学院,南京211101

出　　处：《气象科学》2005年第5期465-473,共9页Journal of the Meteorological Sciences

基　　金：国家自然科学重点基金(编号:NO.40135020)资助

摘　　要：利用1970～2000年6月NCEP/NCAR逐日再分析资料,根据(20～30°N,115～125°E)区域内500 hPa的涡度变化选取了12次西太平洋副热带高压西伸过程,合成了西太平洋副热带高压西伸过程中对流层高层和低层的环流演变特征.结果表明,(20～30°N,115～125°E)区域内500 hPa负涡度的增加对应着西太平洋副热带高压的西伸过程.在副热带高压西伸过程中,对流层高层南亚高压的中心位置虽然稳定少动,但是由于日本东南部反气旋的西移,使得南亚高压东侧的脊明显地加强东伸,这可能对对流层中层副热带高压的西伸具有重要作用.在对流层低层,源于澳大利亚北侧的气流越过赤道向北传播,经由南海季风槽后到达我国江淮流域,从而影响副热带高压西侧的偏南气流.In terms of the NCEP/NCAR 1970-2000 daily reanalysis data in June, 12 westward extension processes of western Pacific Subtropical High are selected based on the variation of 500 hPa vorticity in the key area （20-30 °N, 115-125 °E）. Through composite analysis, the features of the atmospheric circulation evolution from upper to low level of troposphere during the processes of westward extension of western Pacific Subtropical High are investigated in this paper. Results indicate that the increase of the negative vorticity in key area agrees with the westward extension of western Pacific Subtropical High. Another interesting phenomenon is found that the center of South Asia high in the upper level of troposphere is stabile and nearly motionless during the processes of the westward extension of western Pacific Subtropical High, but its eastern ridge strengthens and extends eastward remarkably because the anticyclone moves westward over the southeast Japan, which may lead to the westward extension of Subtropical High in the middle level of troposphere. In the low level of troposphere, the north Australia cold air activity plays an important role in the westward extension of Subtropical High. The flow propagates northward and marches across the equatior, then passes through the trough of summer monsoon over South China Sea and finally gets to the Yangtze River Valley, which sequentially affect the southwest airflow of the west side of Subtropical High.

关 键 词：西太平洋副高 西伸过程 日本东南部高空反气旋 澳大利亚北侧低层气流 

分 类 号：P463.1[天文地球—大气科学及气象学]