湘潭市两次罕见大暴雪天气过程分析

Analysis of Two Rare Blizzard Processes in Xiangtan

【目的】分析湖南省湘潭市2021年12月24日至27日和次年2月21日至22日两次罕见的特大暴雪过程。【方法】采用常规监测数据、分辨率达1°×1°的NECP再分析数据,以及地面GPS/MET遥感大气水汽监测资料进行诊断分析。【结果】两次强降雪过程在大气环流背景和动力学、热力学和水汽输送的条件方面具有相似之处“。12.26”为对流性降雪,降雪时间短、强度大;“02.22”过程以稳定性降雪为主。在湘潭地区,当850 hPa以上温度低于-4℃、925 hPa以下气温在-1℃以下、地面温度接近0℃时,降水相态将由雨转雪。【结论】可为提高湘潭市暴雪预报准确率提供科学依据。

[Purposes]This paper aims to study two rare blizzards in Xiangtan City,Hunan Province,which occurred from December 24 to 27,2021,and from February 21 to 22 of the following year.[Meth-ods]The analysis is made by conventional monitoring data,NECP reanalysis data with a resolution of 1°×1°,and atmospheric water vapor monitoring data from ground GPS/MET remote sensing.[Findings]The two blizzards share similarities in terms of atmospheric circulation background,dynamics,thermodynam-ics,and water vapor transport conditions.However,the"12.26"event was characterized by convective snowfall with a short duration and high intensity,while the"02.22"event was dominated by stable snow-fall.In Xiangtan,when the temperature above 850 hPa is below-4℃,the temperature below 925 hPa is below-1℃,and the ground temperature is close to 0℃,the precipitation phase will change from rain to snow.[Conclusions]The research findings can provide a scientific basis for improving the accuracy of blizzard forecasts in Xiangtan City.