气溶胶对北京地区不同类型云降水影响的数值模拟

Numerical Simulation of Influence of Aerosols on Different Cloud Precipitation Types in Beijing Area

利用耦合Milbrandt双参数显式云方案的WRF模式,在大陆型和海洋型气溶胶浓度背景下,对北京地区暴雨、中雨和微量降水等3次云降水过程进行了数值模拟研究。结果表明,气溶胶的增加对北京地区云降水有多方面的影响:(1)影响地面降水量。随着气溶胶浓度的增加,北京地区的暴雨、中雨和微量降水平均累计降水量分别减少了23.8%,16.6%和14%;(2)影响地面降水分布。在暴雨过程中,随着气溶胶浓度的增加,北京大部分地区的降水量减少了20mm以上。在中雨降水过程中,随着气溶胶浓度增加,降水量增加的面积较大而总降水量减少。在微量降水过程中,随着气溶胶浓度的增加,北京西部的降水量有所增加,东部则减少。气溶胶浓度的增加延迟了暴雨系统中对流云团降水的发生;(3)影响地面雨强。随着气溶胶浓度的增加,暴雨雨强峰值宽度变窄,雨强峰值高度降低,高气溶胶浓度延长了暴雨降水时间。气溶胶浓度的增加导致了中雨降水过程提早结束;(4)影响空中水凝物。气溶胶浓度的增加导致了暴雨和中雨降水过程中云水含量的增加和雨水含量的减少。

Three types of rainfall（rainstorm,moderate rain and slight rain） in Beijing area are simulated using Weather Research and Forecast（WRF3.2） model coupled with Milbrandt-two-moment cloud microphysics scheme,under the continental and maritime aerosol concentration,to explore the influence of aerosols on cloud precipitation.The results indicate that the aerosol increase has various influences on the cloud precipitation：（1） Influencing the ground precipitation.With the increasing of aerosol concentration in Beijing area,48 h total precipitation of the rainstorm and moderate rain are decreased 23% and 16.6%,and 24 h total precipitation of slight rain decreased 14%;（2） Influencing the surface precipitation distribution.The average precipitation of the rainstorm is increased in the most of parts of western Beijing and reduced over 20 mm in the most of parts of eastern Beijing with the increasing of aerosol concentration.The average precipitation of the moderate rainfall decreases 0.1～5 mm in the most of parts of Beijing area. With the increasing of aerosol concentration,the precipitation in western Beijing increase in the slight rainfall process,but eastern,decrease.（3） Influencing the ground precipitation intensity.With the increasing of aerosol concentration the rainfall duration of the rainstorm is prolonged in the high aerosol concentration.An earlier precipitation termination of the moderate rain is found with the increasing of aerosol concentration;（4） Influencing the airborne hydrometeors. The increasing of aerosol concentration causes higher cloud water concentration and lower rain water during the rainstorm and moderate rain processes .