Lightning In Relation To Aerosol Over Eastern China

Time series data of lightning flash density and aerosol optical depth (AOD) have been analyzed, to investigate their spatial and temporal distribution, annual changing trend and seasonal variation over Eastern China. Also, the correlation between them over Eastern China and Nanjing, China has been analyzed. In addition, the multiple regression between lightning flash density and AOD has been discussed to forecast the lightning flash density over Nanjing. The results are as followed.(1) Eastern China located in the high lightning flash density and high AOD value area. Also, the high values mainly appeared in summer season. Furthermore, based on the monthly averaged lightning flash and AOD data of summer season from 2002 to 2011, there is a positive correlation between them (R=0.445).(2) The radiative effect of aerosol may be one of the main reason for the decrease of the summer yearly averaged lightning flash density in a long period, while the aerosol microphysical effect may be a major role in the increase of the percent of+CG flashes (P+cg)-Based on the data from 2002 to 2011, the dependence of surface temperature, CAPE and thunderstorm days on AOD (R=-0.748,-0.741,-0.744), and the negative correlation (R=-0.634) between lightning flash density and AOD may lend support for the radiative effect of aerosol on lightning. In addition, based on the data from 2007 to 2011, elevated aerosols may change the charge distribution in thundercloud, hence enhancing the positive cloud-to-ground lightning (+CG) activity, as P+cg is positively correlated with AOD.(3) Based on the linear fitted formula, the annual mean lightning flash density of summer season over Nanjing, China is evaluated to be 0.088 - 0.031X1 (X1 denotes AOD), which can explain 40.2% of the lightning flash density variation. The average relative error of the formula is 13.99%.