Statistical analysis of tornado activity and environmental characteristics under the influence of tropical cyclones in Jiangsu and Anhui area from 2007 to 2021
This paper collected and counted 65 times of the tornado records in Jiangsu and Anhui Province under the influence of Tropical Cyclone(TC)from 2007 to 2021 including 24 TC(landing)tornadoes and 41 TC(offshore)tornadoes.There are more tornadoes in Jiangsu than in Anhui,more in the south than in the north.The suburbs of the low altitude plain are prone to occur,and the afternoon to evening in July and August are prone to occur.When landing TC causes tornado,the intensity level is mainly tropical depression and tropical storm.Most of them land in Fujian and Zhejiang coastal areas along the northwest route.Tornadoes mostly appear in the northeast quadrant of 300-550 km with TC as the center.There are medium intensity unstable energy,strong low-level shear,and large storm relative helicity and energy helicity in this area.The intensity level of tornado caused by TC at sea is mainly tropical storm,strong tropical storm and typhoon,and there are three main moving paths:the path to the west,the path to the northwest and the path to the north.When TC(offshore)tornadoes occur,TC is mostly in the south of 25°N.At this time,Jiangsu and Anhui regions are jointly affected by the subtropical high and TC,and the southwest warm and wet air flow is continuously transported.In combination with the low trough activity in the middle latitude,the cold and warm air confrontation is conducive to the formation of tornadoes.Although the dynamic conditions are weaker than TC(landing)tornadoes,the thermal conditions are better,and the energy helicity value is larger.
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