Abstract: Based on thunderstorm days data from 1961 to 2015 and Active Divectory Topology Diagrammer (ADTD) lightning location data from 2010 to 2015,the relationship between annual mean cloud-ground lightning density N_g and thunderstorm days T_d was analyzed using a linear model and a power law model throughout different counties in Anhui province.The results were compared with those calculated from formula according to "Code for Design Protection of Structures against Lightning" (GB 50057).The results show that there is no significant difference between thunderstorm days observed from 2010 to 2015 and that observed from 1961 to 2015.The power law model is more suitable for describing the relationship between annual cloud-ground lightning density and thunderstorm days than the linear model.The annual mean cloud-ground lightning density in different counties in Anhui province calculated from the two equations according to the standard (GB 50057) has a large difference from the real observations.The average relative error of the power-law equation N_g=0.024T_d^1.3 is 31.65% and that of linear model N_g=0.100T_d is 44.03%,respectively.The cloud-ground lightning density calculated from the fitting equation N_g=0.0281T_d^1.369 is close to the real observations,and it is more suitable for Anhui province than the other two equations N_g=0.024T_d^1.3 and N_g=0.100T_d.

Key words: Cloud-ground lightning, Thunderstorm days, Lightning density, Error