摘要
利用10 a(2001-2010年)6-8月逐日00 h(世界时,下同)与12 h 700 h Pa高空图及NCEP 1°×1°分析资料,对西南低涡进行了统计与合成分析,总结了影响低涡东移影响湖南的三维环流结构特征。结果表明:1)10 a共有486例西南低涡生成。其中,84例(约17.3%)移出源地影响湖南,7月最多(32例),6月次之(30例),8月最少(22例)。2)影响湖南的西南低涡,其源地主要集中在青藏高原东侧和四川盆地,最易在夜间生成。其大气环流形势表现为:西太平洋副热带高压较弱,位于洋面上;中高纬地区100°E附近为一宽广暖槽控制,槽前的正涡度输送有利于低层减压和气旋性涡度加大;低层整个四川盆地为闭合低压环流控制,东西两边各有一个低压中心存在,西部为暖中心控制,东部为冷舌控制,说明中纬度对流层中高层有冷空气入侵,冷平流使等压面下降促使西南低涡发展东移,这可能是导致西南低涡移出的一个重要环流因子。3)存在三支水汽输送:一支来自孟加拉湾的西南气流的水汽输送,另一支来自南海的偏南和偏东气流的水汽输送,第三支是较弱的西风带气流的水汽输送。
Based on the data of 700 h Pa upper air chart at 00： 00 and 12： 00（ world,similarly hereinafter） and NCEP 1° × 1° analysis data during June to August from 2001 to 2010,statistical and composite analysis were used to analyze the southwest vortexes,the three-dimensional structure of the background general circulation on the development and movement influenced Hunan were studied. Results are as follows. 1） There were total 486 southwest vortexes generating during the 10 years. Thereinto,84 cases（ about 17. 3%） moved out of the birthplaces and influenced Hunan province,which occurred most in July（ 32 cases）,next in June（ 30 cases）,and least in August（ 22 cases）. 2） The birthplaces of vortexes,which influenced Hunan province,concentrated in the east side of Qinghai-Tibet plateau and the Sichuan basin and easily generated in the night. The atmospheric circulation indicated that： west Pacific subtropical high was weak,which located on the ocean; a broad warm trough locates the middle-high latitude region（ 100°E）,the positive vortexes transportation benefited reducing atmospheric pressure and strengthening cyclonic vorticity; the whole Sichuan basin,which was on the low level,was controlled by closed low circulation,and two low pressure center existed on both east and west side. Warm center controlled west and cold tongue controlled east,which showed that cold air invaded at the middle-high level of mid-latitude tropospheric,cold advection lower isobaric surface,which prompt south-west vortexes development eastward,and it is an important circulation factor for south-west vortexes moving out of birthplace. 3） There are three paths of water vapor transport： the first is from the Bay of Bengal＇s southwest airflow,the second is from the South China Sea＇s southerly and easterly airflow and the third is from the westerly.
出处
《气象与环境科学》
2016年第1期59-65,共7页
Meteorological and Environmental Sciences
基金
公益性行业(气象)科研专项(GYHY201206042)
中国气象局预报员专项(CMAYBY2012-038
CMAYBY2015-049)资助
关键词
湖南
西南低涡
合成分析
水汽
Hunan
southwest vortex
composite analysis
water vapor
