A Numerical Study Of The Effects Of Cloud Condensation Nuclei Concentration On Electrification And Lightning Discharges In Thunderstorms

Numerical simulations are carried out to investigate the effect of aerosol on mic ro-physical, electrification and lightning frequency in thunderstorm clouds. A three-d imensional ?3-D? cumulus model with electrification and lightning process is used to investigate the difference of electrification and lightning process.The 3-D cumulus model coupled with an aerosol module is used to simulate a case of tropical convection in Changchun.we chose 12 different aerosol concentration to study. The studies show that aerosol concentration have important effects on electrification and lightning process.The results have been shown as followed. 1) As the aerosol concentration increases,the increase of the number of cloud droplets and the updraft cause the increase of ice crystal number ,but the increasing of rain and graupel is restrained;2)As the aerosol concentration increases,the non-inductive charging rate decreased slightly and delay, while the inductive electrification significantly increased and the duration of electrification become longer; 3) As the aerosol concentration increases , the total number of flashes are increased while the concentration of aerosol increased from 50 cm^-3 to1000 cm^-3,but the total number of flashes are reduced while the concentration of aerosol increased from 1000 cm^-3 to 8000 cm^-3. As the aerosol concentration increases , the electrification process and lightning delay, and the increase of the positive cloud-to-ground flash is more obviously,there are more lightning at the bottom of the central and regional of thunderclouds.In addition,this article selects four autoconversion scheme,and analyzes the microphysical process and the discharge procedure.The results have been shown as followed. 1)The change trend of Dispersion auto-conversion parameterization schemes with the Khairoutdinov-Kogan ?KK? is generally consistent,Dispersion scheme make up for efficiency of reduce by the aerosol, Therefore, we believe that the Dispersion scheme considering spectral dispersion is more reliable for improving the understanding of the aerosol indirect effects.2) The non-inductive electrification rate of Zhijin Hu scheme is the largest, non-inductive electrification rate and the induction electrification rate of Dispersion scheme is larger than KK scheme. And similar to graupel distribution,induction electric rate of KK scheme appear at the latest time, the inductive electrification rate of Sqvt78 scheme is the largest.3) the total number of flashes of Sqvt78 scheme is the most, and the negative cloud-to-ground flash is more obviously. The first charge time of the qvt78 scheme is earliest, and lightning for the longest time. The total of lightning of Sqvt78 scheme is more than KK scheme. The proportion of positive and negative lightning of the qvt78 scheme and KK scheme is the highest, The proportion of positive and negative lightning of Sqvt78 scheme is lowest. The positive and negative lightning more happened during thunder cloud dissipation.