1999—2018年鲁南地区暴雪天气的影响系统及环流特征

利用1999-2018年鲁南地区地面逐日降水资料、NCEP再分析资料，统计了鲁南地区近20年暴雪天气过程，分析了四类影响系统的环流形势和主要特征。结果表明：近20年鲁南地区暴雪过程明显减少；产生鲁南地区暴雪天气的影响系统分为四类，按照发生频次从多到少依次为：回流形势、江淮气旋、切变线和低槽冷锋；回流暴雪灾害重、影响大，11月常出现大范围暴雪，根据500hPa环流形势特征分为高纬低压带型和两槽一脊型回流暴雪，建立了鲁南地区回流暴雪天气模型；江淮气旋暴雪主要发生在2月，影响系统复杂，通常先倒槽降雨，后转为回流形势降雪，揭示了江淮气旋降雪开始与结束时的环流特征；切变线暴雪降水量自南向北减少，以区域性暴雪为主；低槽冷锋暴雪500hPa以下各层低槽比较明显，地面为冷锋，影响系统过境时间短一般降雪量较小。

Influence Systems and Circulation Characteristics of Snowstorm in Southern Shandong during 1999-2018

Based on the daily precipitation data and NCEP reanalysis data from 1999 to 2018 in southern Shandong, the snowstorm weather processes over the past 20 years in southern Shandong are statistically summarized, and the circulation situation and main characteristics of four types of influencing systems are analyzed. The results indicated that the snowstorm process in southern Shandong area has decreased significantly over the past 20 years. The influencing systems of snowstorm in southern Shandong can be divided into four categories, which are Reflux Situation, Jianghuai Cyclone, Shear Line and Low Trough Cold Front in the sequence of frequency of occurrence. The reflux blizzard disaster is serious, which has great impact. In November, large-scale blizzard often occurs, which can be divided into high-latitude low-pressure belt type reflux blizzard and two-trough and one-ridge type reflux blizzard by the characteristics of 500hPa circulation situation, and the model of snowstorm in southern Shandong was established. The Jianghuai cyclonic snowfall mainly occurred in February, the influencing system of which is complex. It usually transforms from the inverted trough rainfall into the reflux situation snowfall, revealing the circulation characteristics at the beginning and end of the Jianghuai cyclonic snowfall. The snowstorm precipitation along the shear line decreases from south to north, which is mainly regional snowstorm. The low-trough cold front blizzard is obvious in each layer under 500hPa, and the ground is cold front, featuring a short transit time of influencing system and generally a small amount of snow.