| To further analyze the relationship between aerosol and lightning activity,data of lightning from satellite and ground-based detection sensors,aerosol optical depth(AOD)from satellite sensor and reanalysis dataset,and meteorological variables(convective available potential energy(CAPE),temperature,and surface relative humidity)from reanalysis dataset were investigated over regions of China in this article.The main results are listed below:(1)The response of cloud-to-ground(CG)lightning to aerosol concentration over the major land area of China was investigated through using nine years(2010～2018)summer lightning detected data and AOD data from MODIS.The results show that the daily CG lightning flashes(daily total CG lightning flashes and daily positive CG lightning flashes)increase with increasing AOD over the majority of study region(>64.7%).This phenomenon is mainly concentrated in the eastern part of China.However,the daily percentage of positive CG lighting flashes(daily positive CG lightning flashes/daily total CG lightning flashes)decrease with the increasing of AOD over the majority of study region(>75%).This trend can be observed over the whole study region.The responses of daily CG lightning flashes and daily percentage of positive CG lightning flashes to aerosol concentration are both weak under polluted conditions.In addition,we also selected five different regions(desert,basin,plateau,plain,and coastal area)of China to investigate the different relationship between aerosol and CG lighting activity.The daily total CG lightning flashes are positively correlated with the AOD over plain(R=0.54)and coastal(R=0.69)areas.A weak positive relationship between them is found over the plateau area(R=0.33).No significant relationships between daily positive CG lightning flashes and AOD are found over the five areas(R<0.30).Except the desert area(R=0.04),the daily percentage of positive CG lightning flashes is negatively correlated with the AOD over the rest areas.(2)Time series data of lightning flash rates,aerosol AOD,surface relative humidity,potential temperature,and CAPE for 14 consecutive summers(2001～2014)over central eastern parts of China(32.5°～40°N,100°～120°E)have been analyzed to investigate the impact of aerosol on the lightning flash rate.The results show that the lightning flash rate is positively correlated(R=0.64)with AOD under relatively clean conditions(AOD<1.0),which may result from aerosol microphysical effect.In the situation of high aerosol concentration(AOD>1.0),the correlation between AOD and lightning flash rate is not obvious(R=-0.06),which may be due to the radiation effect of aerosol.Potential temperature is moderate positively correlated with the lightning flash rate under relatively clean conditions(R=0.51)but shows no significant linear relationship under relatively polluted conditions(R=0.07).CAPE and surface relative humidity are both positively correlated with the lightning flash rates under relatively clean and relatively polluted conditions.(3)The possible effects of two types aerosol(sulfate aerosol and dust aerosol)on CG lighting are investigated over three air polluted areas(R1: 28°～32°N,103°～107°E;R2:29°～33°N,111°～115°E;R3: 34°～38°N,115°～119°E)of China.During months with CG lightning,the GC lighting density is higher under high sulfate concentration conditions over the three study regions,but the changes of CG lighting density under high dust aerosol concentration conditions are not consistent in the three areas.The sulfate aerosol may play the dominated role over the three study regions.The relationships between CG lightning density(percentage of positive CG lightning,PPCG)and sulfate AOD are further analyzed under various CAPE and surface relative humidity bins.The sulfate AOD is positively correlated with CG lightning density under some CAPE and SRH conditions.No obvious correlations are found between them under other conditions,and negative correlations are found between them under a few conditions.The sulfate AOD is negatively correlated with PPCG under most CAPE and SRH conditions. |
