机构地区:[1]陕西省宝鸡市气象局,陕西宝鸡721006 [2]秦岭和黄土高原生态环境气象重点实验室,陕西西安710016 [3]陕西省咸阳市气象局,陕西咸阳712000
出 处:《干旱气象》2023年第5期820-827,共8页Journal of Arid Meteorology
基 金:秦岭和黄土高原生态环境气象重点实验室开发研究基金项目(2021G-26);宝鸡市气象局创新基金项目(202005)共同资助。
摘 要:为探究复杂地形下冬半年降水相态预报方法,进一步提升降水相态预报时空分辨率和准确率,利用2010—2019年冬半年(11月至次年3月)宝鸡市11个国家气象站观测资料及欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料,统计分析宝鸡市冬半年雨、雨夹雪和雪3种降水相态时空分布特征,筛选确定降水相态判识因子及阈值,构建降水相态精细化客观预报方法,并检验预报效果。结果表明:宝鸡市初冬-冬末时期以降雨为主,雨雪转换时期3种相态日数占比相当,而隆冬时期则以降雪为主。降水相态空间分布与地形密切相关,海拔较低的渭河两岸川塬区降雨较多,而海拔较高的南北部山区降雪较多。地面2 m气温(T_(2))、850 hPa和700 hPa温度(T_(850)、T_(700))、850~1000 hPa和700~850 hPa位势厚度(H_(850-1000)、H_(700-850))可作为宝鸡市冬半年降水相态组合判据,川塬区渭滨站初冬-冬末、雨雪转换、隆冬时期雨的T_(2)(H_(850-1000))阈值分别为2.9℃(1307 gpm)、2.1℃(1308 gpm)、1.8℃(1310 gpm),雪的T_(2)(H_(850-1000))阈值分别为0.7℃(1302 gpm)、0.3℃(1303 gpm)、0.7℃(1308 gpm),而山区太白站的降水相态判据不同于渭滨站,降雨时T_(2)(H_(700-850))一般大于2.6℃(1551 gpm),降雪时T_(2)(H_(700-850))一般小于-0.3℃(1540 gpm),雨夹雪的T_(2)、H_(850-1000)、H_(700-850)阈值一般介于雨和雪之间;此外,雨雪相态转换时还需结合T_(850)、T_(700)综合判断。基于温度和位势厚度组合判据构建的宝鸡市不同地形区冬半年各时期降水相态精细化客观预报方法,能够较好地预报2020年11月至2022年1月冬半年逐小时降水相态,TS(Threat Score)值渭滨站达100%,太白站高于80%,优于单一物理量(温度或位势厚度)。In order to explore the forecasting method of precipitation phases in the winter half-year under the condition of complex topography,and further improve the spatio-temporal resolution and forecast accuracy of precipitation phases,the observation data at 11 national weather stations of Baoji City in the winter half-year(from November to next March)during 2010-2019 were used to analyze the spatio-temporal distribution characteristics of precipitation phases including rain,sleet and snow.Combined with the fifth generation atmospheric reanalysis data from European Centre for Medium-Range Weather Forecasts in the same period,the identification factor and its threshold of precipitation phases was selected and confirmed.On this basis of that,a fine objective forecast method of precipitation phases was established,and the prediction effect was tested.The results show that the rainfalls were more during the early and late winter in Baoji City,the proportions of precipitation days with three phases were similar in rain-snow transformation period,while the snowfalls were more in midwinter period.The spatial distribution of precipitation phases was closely relevant to topography,with more rainfalls in low altitude Chuanyuan region on both sides of Weihe River and more snowfalls in southern and northern high altitude mountainous areas.The surface temperature(T_(2)),850 hPa and 700 hPa temperature(T_(850),T_(700))and geopotential thickness from 1000 hPa to 850 hPa and 850 hPa to 700 hPa(H_(850-1000),H_(700-850))were selected to identify precipitation phases in the winter half-year in Baoji City.The T_(2)(H_(850-1000))thresholds of rain were 2.9℃(1307 gpm),2.1℃(1308 gpm)and 1.8℃(1310 gpm)in the early and late winter,rain-snow transformation and midwinter periods at Weibin station in Chuanyuan region,respectively,while the thresholds of snow were 0.7℃(1302 gpm),0.3℃(1303 gpm)and 0.7℃(1308 gpm),respectively.However,the phase identifications at Taibai station in mountainous area were different from Weibin station,the T
分 类 号:P457.6[天文地球—大气科学及气象学]
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