塔里木盆地一次东灌型沙尘暴环流动力结构分析

利用NCEP再分析资料和常规地面观测资料，对2006年4月10日塔里木盆地发生的一次东灌型沙尘暴，从气候背景、环流形势、螺旋度场、锋生次级环流、温度平流等方面进行分析，揭示了此类沙尘暴强盛期的环流动力结构。结果表明：①里咸海脊、乌拉尔脊、新地岛脊同位向叠加，西西伯利亚横槽转竖南下，引导泰米尔半岛强冷空气爆发直插新疆，东灌进入南疆盆地，造成大范围沙尘暴天气；②西西伯利亚地面冷高压爆发性南下并强烈发展是造成此次沙尘天气的根本原因；③盆地前期的干暖形势为沙尘暴的产生提供了有利的热力条件；④沙尘暴区上空螺旋度垂直分布为低层正值、高层负值，构成低空强辐合、高空强辐散的上升运动区，揭示强旋转上升运动是大范围沙尘暴发生的动力条件；⑤高空急流入口区次级环流下沉支导致高层动量下传 ，促使对流层中低层风力加大，冷锋南压，驱动沙尘天气的发生。

Analysis on Circulation Dynamical Structure of a Strong Sand-dust Storm Case from East in Tarim Basin

A strong sand-dust storm occurred in the Tarim Basin during the period from April 10 to 11 in 2006. This paper, using NCEP reanalysis data(horizontal resolution 1°×1°) and the simultaneous conventional observational data, analyzed its climatic background, circulation situation, helicity, divergence, temperature advection and frontogenetical second circulation. The circulation dynamical structure of this type of dust-sand storm was opened out: ①The Caspian ridge, Ural ridge and Xindidao ridge pile up, which causes the polar cold air entering into the Tarim basin and results in sand-dust storms in large extent; ②The eruptive and violent development of west cold Siberian high pressure is the principal cause of strong sand-dust storms; ③The dry and warm situation of the basin in prophase of sand-dust storm provides the advantageous thermal condition for sand-dust storms occurring; ④The vertical distribution of helicity over the sand-dust storm area is negative at the high level and positive at the lower, which imply that the strong rotating climbing movement is the dynamical condition of sand-dust storm occurring; ⑤The downward branch of the circulation in high jet entrance bring the high momentum to the lower layer, increasing the wind speed in the middle and the lower troposphere, pushing the cold front moved southward, and ultimately driving sand-dust storms broke out.