2014年春季一次大风、沙尘、降温、降水的复杂天气分析

Complex Weather Analysis on Strong Wind,Sand- dust,Temperature Drop and Precipitation in Spring of 2014

2014年4月24到26日,呼和浩特地区先后出现了大风、沙尘、降水、降温的复杂天气过程。本文从大气环流场的演变特征、高低层形势场的配置和物理量场特征等进行认真分析认为:切断低涡和地面蒙古气旋是大风、沙尘天气形成的前提条件,地面冷锋是触发条件,沙尘天气主要出现在冷锋附近和冷锋后部;500 h Pa强的斜压槽,加强了动量下传,中低层次级环流是动量下传得以维持的动力系统;冷平流在850 h Pa变形场的作用下制造了寒潮;东南、偏南两股暖湿气流北上,在河套东部一带与冷空气汇合,在700 h Pa与850 h Pa切变线的触发下,制造了降水天气;霜冻出现在高压中心区控制下的早晨,辐射降温形成,高海拔地区较明显。

From April 24th to 26th in 2014, it appeared a complex meteorological process including strong wind, sand -dust, temperature drop and precipitation in Hohhot. In this paper, based on analyzing the evolution characteristics of the atmospheric circulation, configurations of high and low situation field and physical characteristics, it was considered that the prerequisite of forming the weather of strong wind and sand - dust is cutting vortex and Mongolia ground cyclone, surface cold front is the triggering condition, and the dust weather mainly occurs in the vicinity and the rear of the cold front. 500 hpa tilted trough strengthens the momentum downward transfer, and the secondary circulation of the mid - low level is its dynamic system. The cold advection leads to the cold wave under the function of deformation field in 850 hpa. Two strands of warm air from southeast and south move northward and converge with the cold air in eastern Hetao, the shear lines of 700 hpa and 850 hpa trigger the precipitation. Frost appears in the morning controlled under the high pressure central area and radiation cooling forms, which is more obvious in high altitude area.