摘要
利用1953-2012年中国西南地区44个气象台站的逐日降水、温度以及NCAR/NCEP月平均高度场、风场、地面气压、比湿、垂直速度和NOAA月平均海表温度资料,分析了西南地区4~5月持续性干旱的大气环流特征,并对前期印度洋海表温度对西南地区4~5月持续性干旱的影响进行了初步探讨,结果表明:在西南4~5月持续性干旱年,同期4、5月乌拉尔山脊偏弱,东亚大槽南段偏弱,南支槽也偏弱,中高纬西风带偏强,这样北方冷空气和西南暖湿气流均偏弱;对应西南地区表现为异常的下沉运动,同时水汽输送通量表现为异常的辐散中心,从而使得西南地区发生干旱。另外,在西南4~5月持续性干旱年,从前期2月中印度洋异常偏暖的海表温度区逐渐向东移动,在4~5月到达东印度洋,东印度洋异常偏暖的海表温度加热该地区的大气,使得该地区表现出异常的上升运动,导致哈德莱环流增强,而我国西南地区对应异常的下沉气流,从而使得西南地4~5月发生干旱。
With 44 stations temperature and precipitation data of day by day in Southwest China, NCAR / NCEP monthly mean height field, wind, surface pressure, specific humidity, vertical speed, and NOAA monthly mean sea surface temperature data, the potential evaporation was calculated by Thornthwaite method. Through analyz- ing monthly precipitation and potential evaporation percentage proportion spring precipitation from March to May. and taking into account the precipitation and potential evaporation of April and May accounted for the major part ! of the spring, we selected the period of April and May as our research subject and by using homogenization drought index of precipitation and potential evaporation, the persistent drought of spring was defined at first in Southwest China, and then the abnormal years of the persistent drought were determined. By Synthetic analysis method, the atmospheric circulation features of persistent drought over Southwest China from April to May was analyzed. Influence prophase sea surface temperature of Indian Ocean region on persistent drought over the south- west China from April to May was discussed, The results showed that： in the persistent drought years from April to May over Southwest China, Ural ridge Was weak clearly, the southern section of East Asian trough and south branch trough leaned weak over the same period from April to May, but leaned strong westerly in middle and high latitudes, thus the northern cold air of Southwest China＇s influence leaned weak, and the southwest warm and wet air transported to southwest China was also weak. Correspondence vertical movement showed the abnormal down- ward motion over Southwest China,,at the same time the mois^tre transport flux showed abnormal divergence cen- ter, the circumfluence led to drought in the Southwest China. and this circulation features had good continuity from April to May, So persistent droughts occurred over Southwest China in spring. In addition, from the begin- ning of February in the Indian Ocean sea, we obse
出处
《干旱区地理》
CSCD
北大核心
2015年第2期215-222,共8页
Arid Land Geography
基金
国家重点基础研究发展计划项目2013CB430206
公益性行业(气象)科研专项GYHY201306027共同资助
关键词
中国西南
春季
持续干旱
大气环流
海温
southwest China
spring
persistent drought
atmospheric circulation
SST
