2016年12月克拉玛依一次罕见冻雨天气过程分析

本文对2016年12月4-5日新疆克拉玛依市出现历史罕见的冻雨天气过程，通过实况观测资料的综合分析，并利用WRF区域模式进行数值模拟,分析冻雨形成的环流形势、风场、大气层结以及冻雨区云系。结果表明，大尺度环流形势为西风带上弱波动东移，配合中低层西南急流，以及冷暖气团交汇，为冻雨的形成提供了必要的天气尺度条件。本次冻雨的形成机制为融化机制，水汽输送层主要位于冰晶层，水汽受冰晶效应充分凝结后再在暖层融化，落入冷层迅速冷却为冰粒或过冷却雨滴。逆温层是冻雨发生的主要条件，并且随着逆温层减弱，降水物的相态也从冰粒转为过冷却水。本次冻雨过程与南方冻雨不同的是，克拉玛依上空在降水前期就存在强逆温，并且在冻雨发生前逆温层出现减弱再加强的变化。

Analysis of a rare freezing rain weather in Karamay City

In this paper, the author analyzed circulation situation, wind field, atmospheric stratification and clouds through comprehensive analysis of observation data, and numerical simulation using the WRF regional model for a rare freezing rain weather on December 4 to 5 2016 in Xinjiang Karamay City. The results show that the large scale circulation is the eastward movement of the westerly belt, with low level southwest jet and the cold and hot air mass convergence that provides the synoptic conditions necessary for the formation of rain. The formation mechanism of the freezing rain is the melting mechanism. The transfer layer of water vapor is mainly located in the ice crystal layer. The water vapor is fully condensed after the ice crystal effect, and then melts in the warm layer, and falls into the cold layer and is rapidly cooled into ice particles or supercooled raindrops.The temperature inversion layer is the main condition of freezing rain occurred, and with the temperature inversion layer weakening, the precipitation phase is from ice particles into supercooled water. The most different point between freezing rain in Karamay and freezing rains in the southern city is, there is a strong temperature inversion during the prophase of precipitation, and the temperature inversion layer occurs a change from weakening to strengthening before the freezing rain in the sky of Karamay.