北京地区闪电活动与气溶胶浓度的关系研究

Based on the lightning data from Beijing Lightning Network (BLNET) and PM_2.5 data from 35 automatic air-monitoring stations, spatiotemporal distributions of total lightning activities and aerosols have been analyzed in Beijing (39.5°N-41.0°N, 115.0°E-117.5°E). The response of lightning activities to aerosols is further investigated for a total of 117 thunderstorm days. The results indicated both spatial distributions of lightning density and pollutant demonstrated a gradual increase from northwest to southeast of Beijing metropolitan region. The peak lightning activity under relatively polluted condition occurred at 19:00 LT (Local Time), 4 hours later than that (15:00LT) under relatively clean condition, higher aerosol concentration enhanced the percentage of total flashes by a factor of ~2. Correlation analysis of PM_2.5 prior to the occurrence of thunderstorms to lightning density showed a significant positive correlation when PM_2.5 lower than 130 μg•m^-3. This is likely because aerosols enhanced lightning activities by affecting the convective activities through microphysical processes. On the contrary, as PM_2.5 exceeded 150 μg•m^-3, total flashes showed a negative relationship to PM_2.5. This might be attributed to lower solar radiation reaching the surface as a result of increasing aerosol loading. When PM_2.5 ranged from 130 and 150 μg•m^-3, the correlation between aerosols and lightning was very weak, which might be caused by the balance of microphysical and radiative effects of aerosols.