南海和西北太平洋热带气旋闪电活动与对流特征OA

This study compares the lightning activity and precipitation of Tropical Cyclones(TCs)over the closed basin(South China Sea,SCS)and the open ocean(Northwest Pacific,NWP)based on the World Wide Lightning Location Network,multi-source satellite observation,reanalysis data and the International Best Track Archive for Climate Stewardship over the past ten years or more,and explores the physical mechanisms by analyzing convective structure and environmental characteristics.The results show that there is an opposite trend between precipitation intensity and lightning activity of TCs over SCS and NWP.The rain rate of TCs over NWP is higher,and the lightning activity of TCs over SCS is more frequent and asymmetric.In these two regions,the rain rate reaches the maximum on the downshear-left side of TCs,while the lightning density peak moves from the downshear-left side of the inner core to the downshear-right side of the outer rainband.Satellite observations show that the Polarization Corrected Temperature at 85 GHz(PCT85)over NWP is lower,indicating that TCs contain a deeper layer of ice particles or more ice water content,consistent with stronger surface precipitation;however,TCs over SCS show a higher probability of strong radar echo(35 dBZ)appearing above the freezing layer(>6 km),reflecting that the mixed-phase process is more active,which is conducive to lightning bursts.From the perspective of large-scale environmental conditions,higher sea surface temperature and stronger atmospheric instability in NWP are conductive to the development of TCs,forming deeper cloud systems and generating more precipitation.Compared to NWP,stronger vertical wind shear in TCs over SCS makes the convective distribution more asymmetric,and locally forms stronger convection;in addition,thinner warm cloud depth and higher aerosol optical depth in TCs over SCS may suppress the warm rain process in TC convection and enhance its ice-phase process,making lightning occur more frequent.