东北冷涡不稳定能量分布特征及其与降水落区的关系  

Characteristic of Instable Energy Distribution in Cold Vortex over Northeastern China and Its Relation to Precipitation Area

作　　者：陈力强[1] 张立祥[1] 周小珊[1] 

机构地区：[1]中国气象局沈阳大气环境研究所,辽宁沈阳110016

出　　处：《高原气象》2008年第2期339-348,共10页Plateau Meteorology

基　　金：国家自然科学基金项目(40375020)资助

摘　　要：应用地面自动站1 h雨量资料和NCEP再分析资料,以一次典型的东北冷涡过程（2005年7月8～14日）为例,根据冷涡环流特征,将冷涡过程划分为发展期、成熟期、减弱期3个阶段。发现冷涡发展阶段降水主要由其南部西风锋区湿斜压不稳定产生,属于大范围混合型降水;而其他阶段降水主要由对流不稳定产生,以局地对流性降水为主。冷涡的不同发展阶段均可对应不稳定能量区,但其分布有较大差异,对流层低层的暖湿输送及辐合是不稳定能量积累的关键。发展阶段不稳定能量区分布于离冷涡中心较远的东南部;成熟期位于接近冷涡中心东南部;减弱期位于冷涡减弱形成的低压槽中。不同发展阶段不稳定能量与对流降水有不同的对应关系,冷涡发展期对流有效位能与较大的水汽通量是影响降水落区的主要因素;成熟期对流降水基本发生在对流有效位能区和925 hPa湿区的重叠区域;减弱期对流降水不但与对流有效位能、低层相对湿度有关,而且还取决于对流层低层辐合线。Using 1 h rain data observed by AMS and NCEP/NCAR 1°×1° reanalysis data,according to circulation features of a typical case of cold vortex over Northeastern China,the process was divided into 3 phases which were called developing phase,mature phase and weakening phase,respectivly.The precipitation of developing phase was caused by moisture baroclinic instability on westerly frontal zone which belongs to regional mixing precipitation.The other precipitation phases were caused by convective instability,which was main convective rainfall.There is instable energy area within cold vortex in all phases,but it has obvious difference.The warm and moisture air transportations and convergences are key factor to the accumulation of instable energy,so the instable energy area is located in southeast of cold vortex far from center in developing phase,located in southeast of cold vortex near center in mature phase,and in weakening phase instable energy area is located in low trough which evolved from cold vortex.The instable energy brings different convective rainfall in different phases.CAPE and bigger vapor flux are the main elements to decide precipitation area in developing phase.Convective mainly occurs in overlapping area of CAPE and humid area in 925 hPa in mature phase.In weakening phase,convective is not only related to CAPE and relative humidity,but also to convergence line in lower troposphere.

关 键 词：东北冷涡 对流有效位能 降水落区 

分 类 号：P426.6[天文地球—大气科学及气象学]