内蒙古西中部一次春季暴雪特征分析

Analysis on the Characteristics of a Spring Blizzard in the West Central of Inner Mongolia

利用常规气象观测资料和NCEP 1°×1°再分析资料,对2017年3月22日内蒙古西中部一次强降雪过程的相态变化进行成因分析。结果表明:在高低空急流、冷涡、地面倒槽和后部冷锋共同作用而触发此次暴雪;0℃层高度下降,且低层强冷平流的出现并迅速下传,对雨转暴雪天气的预报具有明显的指示意义;对流层中低层风速对水汽辐合具有明显的影响;暴雪过程产生在中高层暖平流,低层冷平流相叠置的区域,为条件性对称不稳定区域;雷达回波强度低,径向速度图中零速度线呈反“S”型,存在冷平流,对降水的相态转化具有指示作用。

Using conventional meteorological observation data and ncepI°×1°reanalysis data to analyze the causes of the phase change of a strong snowfall process in the west central part of Inner Mongolia on March 22,2017.The results show that the snowstorm was triggered by the combined action of high and low level jet,cold vortex,ground inverted trough and rear cold front.The height of the 0℃layer decreases,and the strong cold advection in the lower layer appears and propagates rapidly,which had obvious indicative significance for the forecast of rain to blizzard weather.The wind speed in the middle and lower troposphere has an obvious influence on water vapor convergence.The blizzard process occurs in the area where the warm advection in the middle and high levels and the cold advection in the low levels overlap,which was a conditionally symmetric unstable area.The radar echo intensity was low,and the zero velocity line in the radial velocity map shows an anti“S”shape,with the existence of cold advection,which had a certain indication of the phase transformation of precipitation.