Popular Science Reading： Climatic Characteristics of Tornadoes in China
China Meteorological News reporter Xu Wenbin reports. On the afternoon of June 23, strong convective weather occurred in Funing and Sheyang, Yancheng City, Jiangsu Province, and the local area was hit by a tornado, and many towns and villages were seriously affected. According to Xinhua News, as of 9: 00 on the 24th, the disaster has caused 98 deaths and more than 800 injuries.
Tornado is a kind of small-scale air vortex produced under strong unstable weather conditions. The central wind force can reach 100 ~ 200m/s, and the diameter is generally between several meters and hundreds of meters. After the tornado is formed, it usually lasts for ten minutes to several hours, and the attack range is small, but the destructive power is great.
Temporal and spatial distribution characteristics of tornadoes
From the perspective of spatial distribution, the plain areas in central and eastern China are prone to tornadoes, with Jiangsu and Guangdong having the most tornadoes, with an average of 5.5 and 4.7 respectively. Jiangsu is a tornado in our country (above EF2; Tornado grades are divided into 6 levels, with the smallest level of EF0 and the largest level of EF5). According to the statistics from 1961 to 2010, there were 36 tornadoes with magnitude above EF2 in Jiangsu, including 27 tornadoes with magnitude of EF2, 8 tornadoes with magnitude of EF3 and 1 tornado with magnitude of EF4.
In terms of time distribution, the number of tornadoes from April to August accounts for 92% of the whole year, of which tornadoes in April and July account for 19% and 30% of the whole year respectively. Tornadoes frequently occur from April to May in South China, April and July in the middle and lower reaches of the Yangtze River, June to July in North China, June to August in Northeast China, July to August in Southwest China and July in Northwest China. Tornadoes in Jiangsu occur frequently from June to August, accounting for about 77% of the total in the whole year. Among them, June accounted for about 21%, and the frequent centers were in Rugao, Nantong, Xiangshui and Funing. July is the peak period of tornadoes in Jiangsu, accounting for about 34% of the whole year, and the frequent centers are located in Rugao, Nantong and Hai ‘an. August accounts for about 22% of the whole year. Tornadoes mostly occur in the afternoon to evening, of which 70% occur from 13: 00 to 20: 00, especially from 14: 00 to 17: 00, and the proportion is as high as 60%.
Tornadoes were relatively frequent in China from the mid-1990s to the beginning of this century. According to the statistics of tornado data recorded from 1991 to 2015, there are 42 tornadoes in China every year on average, of which the highest number was 75 in 2005, and the lowest number was 19 in 2014 and 2015. There were relatively many tornadoes from the mid-1990s to the beginning of this century, and there were relatively few tornadoes in China in recent 10 years. Jiangsu has an average of 5.5 tornadoes every year, the highest in 1998, reaching 13; There were relatively many tornadoes from the mid-1990s to 2009.
Tornadoes are destructive and easy to cause casualties.
From 1991 to 2015, an average of 20 people died each year due to tornado disasters in China; In 2005, the death toll was the highest, reaching 57.
In Jiangsu Province, there are 6 deaths per year due to tornado disasters, and the number of deaths in 1966, 1983, 1989 and 2000 exceeded 30 (see attached table).
(Editor: Liu Jia)