曲靖罕见夏秋冬连旱天气分析

RESEARCH ON THE EXTREMELY SEVERE DROUGHT FROM SUMMER TO WINTER OF QUJING CITY

利用1951～2009年沾益测站的降水资料以及NCEP/NCARR的月平均气象场再分析资料分析了2009～2010年曲靖严重干旱天气成因。采用Z指数对曲靖秋冬春连旱异常年份进行划分,表明2009年是夏秋冬连旱最严重的年份。并通过分析曲靖历史上夏秋冬降水偏少年和偏多年的500 hPa高度距平场差值场来为2009年严重的连旱天气提供成因分析,认为:冷空气和偏南气流异常是造成曲靖降水正负异常的成因。2009年夏秋冬季环流与历史上旱年同期的中高纬槽脊强弱分布形势并不一致。从夏季到冬季,贝加尔湖附近位势高度经历了从偏高到异常偏低的变化,孟加拉湾到西太平洋的环流场位势高度持续性异常偏高,暖湿气流缺乏,即使北方有冷空气南下,由于云南下沉运动较常年明显偏强,冷空气也无法与水汽汇合,水汽输送少是产生持续气象干旱的关键原因。

The Causes of the extremely severe drought from summer 2009 to spring 2010 in Qujing are analyzed based on the monthly precipitation data of zhanyi station from 1951 to 2009,the NCEP/NCARR reanalysis data.with the methods of Z index to divided Qujing anomalous years.The results indicate that summer of 2009 is the year of the worst Drought.Analysis 500hPa height anomalies difference of the history rainfall from summer to winter of Qujing typical more years and less years,Results show：the course of the abnormal rainfall characteristics of Qujing Is the abnormal cold air and the Southerly flow.The Circulation background in 2009 was differ from the history drought year at the same time,height in Baikal Has gone from high to low abnormal changes,In addition,from Bengal to the western Pacific Ocean General Circulation Maintain the continuity of abnormally high,lacke of the wet warm air from the Bay of Bengal,Even if the cold air From the north,The downdraft prevailed over the yunnan,the cold airs and warm wet air were not meet,It＇s the key reason for the severe drought.