一次冻雨转暴雪天气的多普勒天气雷达探测分析

Analysis of Doppler Radar Detection in a Weather Process of Freezing Rain and Severe Snow

对2008年1月中旬驻马店市一次冻雨转暴雪天气过程的多普勒雷达的反射率因子、径向速度、风廓线等产品做了详细的分析,发现暴雪回波分布均匀、连续,范围较大,具有明显的丝缕状纹理结构,速度场上0.9～1.6km高度有明显的"牛眼"结构,对应低层强的东北风急流。暴雪时有中尺度垂直环流的存在,当低层偏东风与中高层西南暖湿气流都强时,有利于降雪的发生。冻雨发生时大气具有中层暖、下层冷的温度垂直分布特征和中低空近饱和的深厚湿层,当暖层消失,整层大气温度都在0℃以下时,雨将转雪。

Based on the Doppler radar detection in the freezing-rain and severe-snow days in Zhumadian in mid-January,2008,a detailed analysis has been made on the reflectivity factor,the radial velocity,and the wind profiling,etc.The Doppler radar echo of severe snow is homogeneous,continuous and extensive-range,and has obvious silk-wisp shape characteristics.In the 0.9-1.6 km altitude,there is obvious 'cattle eye'structure,that shows a strong north-easterly low jet there.When the severe snow continues,there are mesoscale vertical circulation currents.When the snow becomes,both the warm wet southwest wind in the high and middle levels and the cold dry northeast wind in the low levels become stronger.When freezing rain happens,the atmosphere is nearly saturated and it is warmer in the middle layer than in the low layer.When the warm layer disappears,the temperature of entire layer is below 0℃,and the rain changes into snow.