景德镇市三类降雪天气概念模型研究

计算并分析了景德镇市出现雨夹雪、一般降雪、大雪（分别简称为Ⅰ类、Ⅱ类、Ⅲ类降雪）形势场、本站要素、层结资料,概括了3类降雪的天气学概念模型。分析结果表明：（1）3类降雪天气过程中,高空500 hPa有强盛的西南偏西气流,且随着降雪强度的增大,西南风速逐渐增大。地面则有较强冷空气堆积,位于贝加尔湖西部的冷高压中心气压在1 050 hPa以上,景德镇处于冷高压底部。925 hPa 30°N附近冷空气势力强,气温低。Ⅰ类降雪的主要影响系统是在江西省北部上空交汇的冷、暖平流,Ⅱ类、Ⅲ类则是850 hPa的切变线,出现Ⅲ类降雪时切变线位于景德镇附近,而出现Ⅱ类降雪时切变线则稍偏南,位于赣中。（2）地面气温变化是降水相态改变的关键,气温越低,越易出现降雪。从大雪至雪后雨,气温逐渐上升。（3）中低层的气温,Ⅱ类降雪较Ⅰ类低;近地面层气温,Ⅲ类降雪与Ⅱ类降雪接近;700 hPa和850 hPa层气温,Ⅲ类降雪比Ⅱ类降雪偏高。（4）Ⅰ类降雪常伴有逆温,但在向Ⅱ类降雪的转换过程中,逆温逐渐减弱,到Ⅲ类降雪时,逆温消失。（5）3类降雪均存在明显的风垂直切变,低层风弱,高层风强,且随着降雪强度的增大,表现愈加明显。

THREE KINDS OF SYNOPTIC CONCEPT MODEL OF SNOWFALL IN JINGDEZHEN

By analyzing the weather situation field, meteorological elements of Jingdezhen station and atmospheric stratification, the synoptic concept models of sleet（type-Ⅰ）, normal snow（type-Ⅱ） and heavy snow（type-Ⅲ） in Jingdezhen city are summarized. The following results show： ① During the three kinds of snow weather process, there are strong southwest airflows at the level of 500 hPa and strong cold airs in the surface layer,and Jingdezhen city is located at the bottom of the cold high pressure. The Type-Ⅰ weather is influenced mainly by intersection of cold and warm advection. The Type-Ⅱ and type-Ⅲ weathers are influenced by 850 hPa wind shear. To type-Ⅲ, the shear is located near Jingdezhen city, while to type-Ⅱ, it is located in Jiangxi central. ② The key factor for precipitation phase change is surface air temperature. The low temperature leads to the emergence of snow more easily. ③ The air temperature of type-Ⅱ is lower than that of type-I at middle and lower level, and the air temperature of type-Ⅲ is little higher than that of type-Ⅱ at 700 hPa and 850 hPa level. ④ A temperature inversion exists for type-Ⅰ, however, there is no inversion temperature layer for type-Ⅲ. ⑤ Vertical wind shear occurs in three kinds of snowfall weather, which presents weak wind speed at the low layer and high wind speed at the high layer.