Analysis Of The Winter Cloud-to-ground Lightning Activity And Its Synoptic Background In China

Winter thunderstorms are less frequent and less studied,but their lightning intensity is high,which can cause serious meteorological disasters.It is urgent to strengthen the research on them.Based on ADTD lightning location data and ERA5 reanalysis data,the spatial and temporal distribution characteristics of thunderstorms and elevated thunderstorms in ten winters in China from December 2010 to February 2020 are analyzed,and their circulation background is analyzed.Finally,a typical elevated thunderstorm case is studied.There are three winter lightning frequent areas,located in the southwestern Yunnan province(WLA1),the western Hunan province(WLA2),and the northern Jiangxi province(WLA3).The diurnal variation of winter lightning in China is more frequent at night,and the intermonthly variation is more frequent in February.The weather situation of winter thunderstorm in China includes frontal and non-frontal type.The weather situation of non-frontal pattern mainly occurs in Yunnan Province.The weather patterns with front can be further divided into four typical types:Transversal Trough After High Pressure,Low Vortex,Confrontational Convergence,and Asymptotic Convergence.Elevated thunderstorm is a common form of winter thunderstorm in some areas of China.Most winter elevated thunderstorms occur in the northwest of Hunan province and its surrounding areas,and almost all winter thunderstorms in this region are elevated.Compared with surface-based thunderstorms,the intensity of lightning in elevated thunderstorms is stronger,and the proportion of positive lightning is lower.Through a typical case study,it is found that elevated thunderstorms are accompanied by strong upper-level jet,the lightning area is located in the left front of the upper-level jet axis exit area,and the water vapor transport is mainly concentrated in the level of 850 h Pa to 700 h Pa.The uplifting mechanism of the elevated thunderstorm includes terrain and front,and the convective instability could not explain the process of the elevated thunderstorm.