Characteristic Analyses on Environmental Parameters in Short-Term Severe Convective Weather in China

The characteristics of environmental parameters of severe short-term precipitation,large hail,severe thunderstorm winds and the co-existence convective weather in China are studied,based on the rainfall data from more than 2 000 national weather stations and part of the sounding data during 2002-2011.The conclusions are:(1) The following parameters,including the shape of stratification and dew curve,the temperature difference between 700 hPa and 500 hPa,the temperature difference between 850 hPa and 500 hPa,the height of 0 ℃,-20 ℃ and balance layer,the dew point temperature on the surface and at 1.5 km height,the temperature-dew point spread on 1.5 km height,the convective available potential energy(CAPE) and the vertical wind shear in 0~6 km,can be used to effectively distinguish the environmental background of the four types of severe convective weather.(2) Differences of the environmental background are relatively significant between the pure short-term heavy rain(including type I,II) and large hail and severe thunderstorm winds.Comparing with the latter,the former has smaller temperature difference between 700 hPa and 500 hPa,smaller temperature difference between 850 hPa and 500 hPa,weak vertical wind shear,relatively high altitude of 0 ℃,-20 ℃ and balance layer,larger dew point temperature on the surface and 1.5 km height.The type I(accounting for the majority of the short-term heavy rain),with its higher relative humidity at the whole layer,is obviously different from the others.(3) Co-existence severe weather is similar to the large hail weather and the severe thunderstorm wind weather,in the following aspects: The shape of stratification and dew curve,the value of CAPE and the 0~6 km vertical wind shear.There is an obvious dry layer at the middle troposphere and larger value of CAPE and shear.However,the co-existence weather has relatively high altitude of balance layer,larger dew point temperature on the surface and the 1.5 km height and smaller temperature difference between 850 hPa and 500 hPa.In these respects,the co-existence weather is closer to the pure short-term heavy precipitation.