河北省廊坊市初冬雨雪相变特征及预报指标初探

Analysis on Phase Transformation Characteristic of Rainfall and Its Prediction Index in Langfang of Hebei Province in Early Winter

利用河北省廊坊市45 a的地面气象观测资料,分析了河北省廊坊市区初冬雨雪相变的天气气候特点。利用Micaps常规资料、新一代多普勒雷达资料、自动站资料,对近年来廊坊市出现的典型雨雪相变天气过程的环流背景、物理量场和雷达资料进行综合分析表明:500 hPa西来低槽(涡)、700hPa和850 hPa切变、地面倒槽等影响系统共同作用是河北省廊坊市雨雪相变天气过程的典型形势。0℃层在950 hPa可作为雨雪转换的临界面,北京多普勒天气雷达上0℃层亮带高度迅速下降后1～2 h内,即可以推断廊坊降水相态将由雨转为雪。

Based on the data of precipitation from 1965 to 2010, the climatic characteristics of the phase transformation of rainfall in Langfang area in Hebei Province are analyzed. The main results indicated that the interannual variation of station numbers occurring phase transition from rain to snow weather processes was bigger, and most in November and March, and the main circulation types were two troughs and one ridge and westerly trough （votex）. Based on micaps routine data, a new generation Doppler radar data and observations from automatic weather stations, the circulation background, physical quantity field were analyzed about the typical phase transi- tion weather processes occurring in Langfang in recent years and results show that the influence systems＇interaction of 500 hPa westerly trough（votex）, the shear line on the level of 700 hPa and 850 hPa and surface trough was main typical circulation of those weather processes. According to the echo characteristics of Doppler radar in Beijing, after one to two hours when the height of the 0℃ layer bright band decreases quickly, Langfang would occurr phase transition from rain to snow weather.