一次春季暴雪天气不稳定机制及相态成因分析  

The Instability Mechanism and Cause Analysis on the Precipitation Phase of a Blizzard in Spring

作　　者：孙鑫 Sun Xin(Inner Mongolia Meteorological Observatory,Inner Mongolia Hohhot 010051)

机构地区：[1]内蒙古自治区气象台,内蒙古呼和浩特010051

出　　处：《内蒙古气象》2024年第3期3-11,共9页Meteorology Journal of Inner Mongolia

基　　金：呼伦贝尔市科技计划项目(SF2022013)。

摘　　要：利用常规观测资料、NCEP/NCAR 0.25°×0.25°再分析资料和FY-2G TBB资料,对2020年4月19—21日内蒙古一次降雪天气过程的不稳定机制及相态成因进行分析。结果表明:(1)本次天气过程降雪量大、降水相态复杂,多站降雪刷新了4月降水量历史极值;(2)500hPa高空冷涡及地面气旋是本次天气过程主要影响系统;(3)850hPa至地面的东北气流为本次降水提供冷垫,使得上层暖湿气流沿着冷垫爬升,属于一次冷季高架对流过程,条件性对称不稳定导致的倾斜对流造成了极端降雪的发生;(4)地面温度≤0℃、925 hPa气温≤0℃,850 hPa的气温≤-3℃可以作为本地极端降雪相态发生转变的预报指标值;(5)降水相态分界线与700 hPa暖式切变线位置密切相关,随切变线的南压而南压;(6)冷空气自北向南入侵,0℃层下降是此次天气过程降水相态发生变化的原因之一。Based on conventional observation data,NCEP/NCAR 0.25°×0.25°reanalysis data and FY-2G TBB data,the formation mechanism of an extreme snowfall weather process in northeastern Inner Mongolia during April 19-21,2020 was analyzed.The results showed that:(1)The snowfall in this process was large and the precipitation phase was complicated.Several meteorological observing stations reported record-high precipitation in April.(2)The snowfall mainly caused by Cold vortex at 500 hPa and surface cyclone.(3)There was a northeast airflow between 850 hPa and ground that could be used as a cold cushion for the warm humid airflow at upper layer to climb along,leading to an elevated convection process in cold season.The tilted convection caused by conditional symmetric instability led to the extreme snowfall.(4)Tsurf≤0℃,T925≤0℃,and T850≤-3℃were three forecast index values of precipitation phase transformation.(5)The spatial boundary of precipitation phase was closely related to the location of the warm shear line at 700 hPa,and it moved with the shear line.(6)With the invasion of cold air from north,the descent of zerotemperature layer was one of the reasons for the change of precipitation phase.

关 键 词：条件性对称不稳定 高架对流 0℃层下降 

分 类 号：P458.121.1[天文地球—大气科学及气象学]