内蒙古中西部地区一次沙尘暴天气的动力诊断

Diagnosis of a Sand Storm Weather Process Occurred in Inner Mongolia in 2009

用多普勒天气雷达探测资料、地面沙尘暴探测资料、卫星图像和常规气象资料对2009年4月23日发生在内蒙古中西部地区一次大风、扬沙及沙尘暴天气过程进行了连续监测和分析。结果表明:高空槽发展加强,强锋区南压,地面冷锋影响,气压梯度大是造成沙尘暴的天气形势。红外图像形成"沙尘羽",结构均匀有纹理,云顶亮温出现<-60℃区域是卫星图像特征。雷达回波显示,反射率因子>30 dBZ,影响高度2.4 km以上;径向速度图上出现明显辐合辐散特征,强风区增大,上升运动及下沉运动加强;高空有垂直风切变,高度降低厚度增加,能量增加,当垂直风切变变小时,高空动量开始下传,沙尘天气开始。地面沙尘暴探测资料显示,空气中质量浓度的最高值出现在沙尘天气最强及极大风速出现时刻,最大值达8 223.7μg.h-1,比沙尘天气出现前81.8μg.h-1高出100倍,沙尘天气造成空气相当混浊。

Based on Doppler weather radar data,surface dust observation data,satellite images and meteorological data,a strong wind,blowing sand and dust storm weather process occurred in central and western Inner Mongolia on 23 April 2009 was monitored and analyzed.The results showed that strengthening and developing of the upper trough,moving to south of the strong frontal zone,the influence of the surface cold front and the big pressure gradient resulted in this weather process.The ＂dust feather＂ occurred and well-proportioned structure with texture,and the TBB -60 ℃ region appeared in the satellite images.Radar echoes showed the reflectivity factor was more than 30 dBZ,the significant convergence and divergence character presented in radial velocity image and the strong wind zone increased,the upward and downward movement strengthened;the vertical wind shear occurred in the upper level,when it decreased the upper momentum started to transport downward and dust weather occurred.Ground dust detecting data showed that the maximum of mass concentration（8 223.7μg·h-1）in air appeared when wind speed was the largest,which was 100 times more than that of the onset of dust weather.