Environment Parameter Characteristics of Different Types of Cold Season Elevated Thunderstorms in Hubei
Based on conventional observation data,data from intensive automatic ground stations,lightning location data,and NCAR reanalysis data,we analyzed the weather types,spatial-temporal distribution,and environmental conditions of cold season elevated thunderstorms in Hubei from 2011 to 2020.Moreover,we discussed the environmental parameter characteristics of different types of cold season elevated thunderstorms according to the results in boxplots.The main results are as follows:(1)Cold season elevated thunderstorms in Hubei,occurring from November to March the following year,can be categorized into thunderstorm,severe convection,and thundersnow.The spatial distributions of cold season elevated thunderstorms were uneven:there were seasonal and regional differences in the spatial-temporal distribution of different types of cold season elevated thunderstorms.The thunderstorm type occurred mostly in November,January,and February,the strong convective type and thundersnow type usually appeared in early spring(February),and the strong convective type was dominant in March.(2)The low trough cold front,850 hPa shear line,and low-level southwest jet were favorable circulation backgrounds for the occurrence of overhead thunderstorms in the cold season.The low-level southwest jet was controlled by stable cold air mass near the surface,and the temperature inversion was obvious.The uplift of the low-level southwest jet was triggered along the front inversion layer near 850 hPa,and water vapor,ascending motion,and unstable stratification all appeared above 850 hPa.The distance between thunderstorms and thundersnow was more than 100 km,and the distance between severe convection was less than 100 km.(3)850 hPa was an important level of wind field transformation.The maximum dew point temperature(Td850),K index,temperature difference between 850 hPa and 500 hPa(ΔT85),false equivalent potential temperature(θse850)of 850 hPa,southwest jet stream thickness and intensity(I700),and shear line intensity(S850)were observed in the severe convection type,while the minimum vertical wind shear(SL78)was observed in the middle and lower layers(850-700 hPa).The thundersnow type had the lowest requirement for water vapor and unstable energy,while the SL78 was the highest.
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