昆明冬季降水相态识别判据研究

Study on Identification Criterion for Precipitation Phase in Winter Kunming

利用昆明气象站1952—2013年冬季的降水及天气现象资料,统计分析了昆明冬季降雪的气候特征。利用1980—2013年高空、地面资料,选取500 hPa温度、700 hPa温度、0℃层高度、500~700 hPa之间的位势厚度、地面日最低温度和日平均温度6个物理量,针对雨和雪的降水相态进行统计分析,采用降雪TS评分最高的原则确定物理量的阈值。对每个单一判据给予不同的权重,采用权重线性法设定降雪的综合判据,通过对6个物理量降雪判据进行不同的组合试验,并考虑到综合判据的业务化,最终选定700 hPa温度、500~700 hPa之间的位势厚度、地面日最低温度3个单一判据组合为综合判据,并用中尺度WRF模式对2014年的13次降水天气进行了降水相态判别检验,结果表明综合判据可为昆明冬季降水相态客观预报提供较好的参考。

Based on precipitation and weather phenomena data from Kunming Station in winter from 1952 to 2013,the climatic characteristics of winter snowfall in Kunming are analyzed.In addition,using surface and upper air data,six physical quantities such as temperature at 500 and 700 hPa,0℃ level height,geopotential thickness between 500 and 700 hPa,daily lowest and average temperature at surface are selected.The phase of precipitation and snow is analyzed,by using the principle of highest TS score to determine physical quantities' threshold range.Different weights are offered to each criterion,using weight linear method to set synthetic criterion of snowfall,through different combined experiments on snowfall criterion of six physical quantities,and considering the operational application of synthetic criterion.Finally,three single criterions are selected,that is,temperature at 700 hPa,geopotential thickness between 500 and 700 hPa and daily lowest temperature at surface,and combined into synthetic criterion.In addition the precipitation phases during 13 rainfall weather processes in 2014 are tested by using WRF model.The results show that synthetic criterion could provide valuable reference for objective forecast of precipitation phase in winter,Kunming.