北京地区冻雨时空分布及探空温湿特征分析

Analysis of Spatio-Temporal Distribution and Sounding Temperature-Humidity Characteristics of Freezing Rain in Beijing Area

利用1955年1月至2013年4月北京地区常规地面观测和南郊观象台探空资料,根据地面观测冻雨记录,分析了时空分布规律;依据冻雨发生时探空资料,初步分析了温湿结构特征和形成的物理机制类型。选取2000—2013年11月至次年4月常规地面观测和南郊观象台探空资料,根据地面观测降雨、雨夹雪、降雪记录,分析了与其对应的南郊观象台平均探空温湿结构,并与冻雨进行比较。结果表明,北京地区冻雨多发生在西北部和东南部,从11月开始至次年4月结束,并以暖雨机制为主(86.4%);850 hPa以下温度层结曲线准垂直,且<0℃是北京地区冻雨的主要特征;雨夹雪和冻雨的主要差异在850 hPa以下,低层雨夹雪气温高于冻雨。

The spatio-temporal distribution of freezing rain in Beijing is analyzed by using the surface observation data and sounding data from 1 January 1955 to 30 April 2013.The temperature-humidity structure and the formation mechanism type of freezing rain are studied using the sounding data.Comparative analysis of the temperature-humidity structure and its difference from freezing rain,rainfall,sleet and snow is done using the observation data collected from November to April in 2000 — 2013.The results show that freezing rain is prone to occur in the northeast and southeast of Beijing,from November to the next April,of which about 86.4%is warm-rain mechanism.The temperature stratification curve under 850 hPa is nearly in vertical and the temperature is below 0℃,which is the main characteristics of Beijing regional freezing rain.The main difference between sleet and freezing rain is the temperature under 850 hPa,the temperature of sleet is higher than the freezing rain.