沙颍河流域一次基于高分辨资料的降水相态分析  

Analysis of a Precipitation Phase based on High-Resolution Data Occurredin Shaying River Basin

作　　者：武威 胡燕平 WU Wei;HU Yanping(Luohe Meteorological Bureau,Luohe 462300,Henan,China;Sha-Ying river basin meteorology center,Luohe 462300,Henan,China)

机构地区：[1]河南省漯河市气象局,河南漯河462300 [2]河南省沙颍河流域气象中心,河南漯河462300

出　　处：《高原气象》2019年第5期983-992,共10页Plateau Meteorology

基　　金：河南省气象局预报员专项(KY201932);沙颍河流域气象科技创新团队项目

摘　　要：利用常规气象资料、NCEP 0.25°×0.25°分析资料以及微波辐射计、风廓线雷达等高分辨率资料,采用诊断和统计方法,对2017年2月21日沙颍河流域一次雨雪过程中降水相态进行分析。结果表明:在高空低槽与东路冷空气共同作用造成雨雪天气的背景下,925 hPa及以下冷高压底部的偏北冷空气造成低层持续降温,导致降水相态变化。过程前期700 hPa以下为强暖平流,冷平流在900 hPa以下且较为浅薄,温度层结为冷层-暖层-冷层-暖层,冰晶粒子下落融化形成雨滴。降水中后期冷平流发展强烈导致温度迅速下降,整层温度变为冷层,导致相态为雪;即使下游局部地区仍有暖层,但暖层浅薄、低层冷层深厚,相态也为雪。雨雪转换时0℃层高度下降明显,降雨阶段0℃层在抬升凝结高度以上,降雪阶段0℃层降到抬升凝结高度以下;0℃层亮带回波在相态转换时出现明显变化,其亮带高度逐渐降低。微波辐射计的温湿廓线、云底高度以及液态水等在雨雪转换中均有显著变化,液态水含量在雨雪转变时迅速增大。风廓线风场定性反映了冷空气持续南下,低层冷垫增厚,导致相态转变以及降水强度增加;风廓线速度定量反映出降雨和降雪之间的差异,降雨速度范围为1.5~7.0 m·s^-1,降雪速度范围在0.25~1.5 m·s^-1;雨雪转换时下落速度明显减小,可用于相态转变的监测和预报。Based on the conventional meteorological observation data,NCEP 0.25°×0.25°analysis data and the high-resolution data from the microwave radiometers and the wind profile radars,the precipitation phase of rain and snow process in the Sha-Ying river basin occurred on 21 February 2017 was analyzed using diagnostic and statistical methods.The results showed that the transition of precipitation phase was caused by continuous cooling in the lower layers,which was induced by northerly cold air at cold high bottom below 925 hPa,in the background of the rain and snow weather caused by interaction of the upper air trough and easterly cold air.In the earlier stage of this process,there was a strong warm advection below 700 hPa and a shallow cold advection below 900 hPa.The temperature structure of the whole layer was cold-warm-cold-warm,which led to the ice crystals melting into raindrops while falling.In the medium and latter stages,the strongly development of cold advection led to temperature rapidly decreasing,so the entire temperature layer turned to cold,and the phase state turned to snow.Although there was a warm layer in the local area,the phase was also snow as the warm layer was shallow and the lower cold layer was deep.The height of the 0℃layer decreased significantly during the rain-snow transition.The 0℃layer was above the LCL in the rainfall,and fell below the LCL in the snowfall.The bright band echo at 0℃layer showed a significant change in the precipitation phase transition,whose height gradually decreased.The temperature and humidity profiles,the cloud base height and liquid water from the microwave radiometer all showed significant changes in the rain-snow transition.The liquid water showed rapid increase in the rain-snow transition.The wind profile qualitatively reflected the cold air moving southwards continuously,and the cold lower layer became thicker,led to the increase of precipitation intensity and the change of phase state.The wind profile velocity quantitatively reflected the difference bet

关 键 词：降水相态 温度平流 0℃层 微波辐射计 风廓线雷达 

分 类 号：P457.6[天文地球—大气科学及气象学]