1955-2019年辽宁龙卷时空分布特征

Spatial and Temporal Characteristics of Tornadoes in Liaoning Province from 1955 to 2019

为研究辽宁地区龙卷气候特征,基于《中国气象灾害大典》《中国气象灾害年鉴》和其他相关资料,采用“改进藤田分级”标准进行强度分类,对1955-2019年辽宁龙卷的时空分布特征进行统计分析,得到以下主要结论:(1)1955-2019年辽宁地区平均每年出现龙卷2.3个,年龙卷密度为1.5×10个/km~2,约为美国的1/10。EF2及以上等级强龙卷共记录到25次,年均0.4次,含EF4级1次,EF3级3次,EF2级21次,相邻分级比例在0.1~0.36。(2)龙卷主要出现在5-10月,其中7月最多,超过年总数的1/4。龙卷大多出现在午后到傍晚,13-14时、17-18时是两个龙卷多发时段。约85%的龙卷事件持续时间在20分钟以内。(3)多数龙卷发生在平原地区,5-6月多分布于辽西走廊至辽宁西北部地区;7-8月集中于辽西走廊和辽河平原中下游地区;9-10月辽宁东部地区龙卷明显增多。

In order to study the characteristics of tornadoes in Liaoning province,based on " the Handbook of China Meteorological Disasters",and "the Annual Report of China Meteorological Disasters" and other related data,the intensity classification was carried out by using the standard of improved Fujita Classification,the temporal and spatial distribution characteristics of tornadoes in Liaoning from 1955 to 2019 were statistically analyzed.Given the study results,(1) From 1955 to 2019,there is a mean of 2.3 tornadoes annually in Liaoning,meanwhile,the annual average tornado density is1.5×10/km~2,which is about 1/10 of that in the United States.There is a total of 25 significant tornadoes of EF2 and above were recorded,with an average annual occurrence of 0.4,including one time of grade EF4,3 times of grade EF3,and 21 times of grade EF2.The ratio of adjacent grading is within the range of 0.1-0.36.(2) Tornadoes occur with a maximum from May through October and more than a quarter of the annual total occurred in July.Tornadoes mostly occur in the afternoon to the evening.13:00-14:00 and 17:00-18:00 are two frequent periods of tornadoes.Approximately 85% of tornado events last within 20 minutes.(3) Most tornadoes occur in the plains,while tornadoes are distributed from the Liaoxi Corridor to northwestern Liaoning area from May to June,in the Liaoxi Corridor and the middle and lower reaches of the Liaohe Plain from July to August and increased significantly in the eastern coastal area of Liaoning from September to October.