山东冬半年降水相态的温度特征统计分析  

Analysis on Temperature of Precipitation Types in Cold Seasons in Shandong

作　　者：杨成芳[1] 姜鹏[1] 张少林[1] 张磊[1] 

机构地区：[1]山东省气象台,济南250031

出　　处：《气象》2013年第3期355-361,共7页Meteorological Monthly

基　　金：国家自然科学基金(41175044);山东省气象局重点课题(2010sdqxzl0)共同资助

摘　　要：采用济南和青岛1999—2011年的降水、高空和地面观测资料,研究了山东冬半年降水相态与影响系统的关系及温度垂直变化特征,获得不同降水相态的温度预报指标。结果表明:(1)降水相态变化与影响系统有关,江淮气旋和回流形势产生的大雪以上强降雪存在雨雪转换,低槽冷锋、黄河气旋和切变线(低涡)多产生中雪以下直接降雪。(2)无相态变化的降雪过程一般发生在温度较低、垂直变化单一的条件下,850 hPa以下各层均有明显温度阈值。(3)有相态转换的降雪过程中,850和925 hPa的温度对于雨、雪、雨夹雪的识别没有明显指示性,1000 hPa以下的温度最为关键,将925 hPa以下各层与地面的温度结合起来判别相态,较使用单一特性层温度更为可靠;冰粒区别于其他降水类型,在温度场上的显著特征为700 hPa的温度较高。(4)0℃层高度可用于雨雪转换指标:降雨时0℃层高于925 hPa或在925 hPa上下,当0℃层的高度降至1000 hPa上下时转为降雪。(5)雨夹雪和冰粒发生在有雨雪相态转换的降水过程中,为过渡形态,不会单独出现。This study uses daily observation data in Jinan and Qingdao, Shandong Province during 1999-- 2011, to reveal associations between the precipitation types and temperatures to determine potential changes of precipitation in cold seasons. The results show that precipitation types are firstly relative with synoptic systems. Jianghuai cyclone and backflow situation weather systems often produce different precipitation types. Cold fronts, Huanghe cyclone and low eddy shear line often lead to snowfalls directly. Pure snowfall occurs in low temperatures and has obvious thresholds below 850 hPa. Temperatures at 850 hPa and 925 hPa are weak clues for identifying rain, snow and sleet in mixed precipitations while temperature below 1000 hPa is very critical. It is better for precipitation type discrimination by combining the temperature in different levels under 925 hPa with surface temperature than the single level temperature. By comparison, ice pellets are highly dependent on the higher temperature in 700 hPa. The height of 0℃ level is good clue for predicting precipitation types. The 0℃ level is higher or near 925 hPa when it rains, but when it descends near 1000 hPa rain converts to snow. There is no pure sleet or ice pellets because they always appear in mixed precepitation types.

关 键 词：降水相态 影响系统 雨雪转换 温度指标 

分 类 号：P426[天文地球—大气科学及气象学]