一次强沙尘暴和雪暴天气过程的诊断及模拟分析

利用基本气象资料和T213数值预报产品资料,对发生在内蒙古大部分地区的一次强风、强沙尘暴、强雪暴和强降温天气过程进行了动力诊断和模拟分析。结果表明,强冷空气活动是造成多种灾害的主要动力,高空急流是强风的动量来源,蒙古气旋强烈发展造成的气压梯度风加剧了地面大风和沙尘暴。强烈的冷、暖平流空间配置使大风、沙尘暴和降温更为剧烈。散度场的空间配置有利于沙尘暴、暴风雪的发展。高空西风急流对低空西南急流具有耦合和触发作用,低空西南急流的建立和长距离的水汽输送与辐合,成为内蒙古东部产生暴雪的重要条件,低层东风切变带中的正涡度平流的输送,叠加到了较好的水汽输送及辐合区域,加大了降雪。后期低层西北急流的形成,是产生暴风雪的重要原因。数值模拟结果表明,模拟高压、低压中心位置和强度与实况较为吻合,气旋的气压梯度强度与实况较为接近;冷暖平流在分布区域、输送方向、强中心位置上也与实况具有较相似的特征,但是温度平流模拟的结果在量值上略大于实况。

Dynamic Diagnoses and Simulating Analysis of a Severe Sandstorm and Snowstorm Weather Process

Adopting the basic meteorological data and T213 numerical prediction productions,the dynamic diagnoses and simulating analysis of weather process mixed with strong wind,sandstorm,severe snowstorm and temperature decreasing in Inner Mongolia.The results shows that the strong cold air action is the main dynamics factor and the upper jet stream is the momentum source of the wind.Pressure gradient wind caused by developing Mongolia cyclone strengthen the wind and sandstorm.The space allocation of intense cold,worm advections intensify the strong wind,sandstorm and temperature decreasing.The space allocation of divergence helps the sandstorm and snowstorm developing.There is trigger and coupling actions for upper westerly jet to lower southwest jet.The establish of lower southwest jet and long distance vapour transportation and convergence are the important condition for east Inner Mongolia occurring snowstorm.The positive vortex advection transport in lower east wind shear zone superpose better vapor transportation and convergence area which enhances the snowfall.The later formation of northwest jet at bottom is important reason of the snowstorm.Numerical simulation shows that the location and intensity of the modeled high and low pressure centers is consistent with the observation.The pressure gradient intensity of cyclone closes to observation.The regional distribution,transportation direction,centers of the cold,worm advections have similar characters with fact.On the other hand,the temperature stratosphere simulation result is slightly bigger than the fact.