重庆春季连阴雨的气候特征和气候信号分析

Analysis on Climatic Characteristics of Spring Continuous Rain in Chongqing and Its Relationship with Climatic Signals

利用1961—2012年3—5月NCEP/NCAR再分析资料、NOAA的海温、重庆34个站气象资料和74项环流特征指数,分析了重庆春季连阴雨的时空变化特征及其与同期的大气环流、西太平洋副热带高压(西太副高)、前期冬季的海温、OLR、大气环流以及西太副高之间的关系。结果表明:重庆春季连阴雨有发生频率高的特征,3月最容易发生影响范围广,持续时间长的连阴雨,其次是5月。连阴雨明显的时段重庆受影响的范围广,持续时间较长,气温偏低。东北部和西部地区出现频次较低,东南部较高。连阴雨分布主要为全市一致型和东西相反型。春季巴伦支海地区和青藏高原的500 hPa高度场偏低,贝加尔湖以东地区偏高,欧亚中高纬环流形势有利于冷空气南下和西太副高的减弱东退是重庆的连阴雨发生的主要因素。冬季拉尼娜事件的发生、赤道150°E地区的对流加强和鄂霍次克海地区中高层大气高压脊的建立都有利于来年春季重庆连阴雨的发生。

Based on the NCEP/NCAR reanalysis data,sea surface temperature（SST） of NOAA,index of74-term circulation characteristics and weather observation data from 34 stations of Chongqing over 1961—2012,the climatic characteristics of spring continuous rain in Chongqing,the climate impact factors of the same period such as atmospheric circulation,the West Pacific subtropical high and early winter impact factors like SST,OLR,atmospheric circulation and the West Pacific subtropical high were analyzed.The results indicated that the spring continuous rain has so high frequency that Chongqing suffers serious spring continuous rain easily in March,followed by May.During the serious continuous rain period,the impacted range and the maintained time expanded.Furthermore,the probability of low temperature increases obviously.From the spatial distribution,the frequency of the spring continuous rain is high in Southeast China,but is relatively less in the northeastern and western parts.The spatial distribution of the continuous rain include two types：consistency in all areas and contrary in the west and east parts.In spring,lower500 hPa geopotential heights are on the lower side in Barents Sea and the Tibetan Plateau region,higher in the east of Baikal Lake region,the general circulation anomalies over Eurasia mid-high latitude is beneficial to southward movement of cold air,and the West Pacific subtropical high weakens and retreats to east and south,which are the main factors for the occurrence of continuous rain in Chongqing.In early winters,the occurrence of the La Nina event,the development of the convection in the 150°E equator region,the establishment of high pressure ridge in the upper atmosphere in Okhotsk Sea area are conducive to the occurrence of spring continuous rain in Chongqing.