气溶胶污染对夏季降水精细数值预报的影响研究

Impacts of aerosols on the fine-scale numerical forecasting of summer precipitation

本文基于北京地区快速更新循环同化和预报系统(BJ-RUC),通过对北京2014年汛期的32次降水过程进行数值模拟和敏感性试验,研究了气溶胶污染引起的云滴数增加对北京夏季降水精细数值预报的影响.研究结果表明:BJ-RUC系统中默认的云滴数浓度偏低,采用根据环境模式预测结果计算的云滴数浓度后(BJ-RUC-Nc算例)预报效果更接近实况;气溶胶增多可以增加或减少降水.具体表现在:(1)2014年汛期北京地区降水主要集中在东北区域(平谷、密云、顺义)、城区次之,数值模式能较好的反映出降水的整体分布和趋势;(2)BJ-RUCNc对于小雨、中雨、暴雨的预报优于BJ-RUC,更接近观测;(3)气溶胶浓度增加,当水汽供应充足(不足)时,会促进(抑制)降水性粒子形成,降水效率提高(降低),降水增加(减少).

Thirty-two precipitation processes of Beijing in flood season of 2014 were numerical simulated and sensitively tested by using Bei Jing Rapid Update Cycle of assimilation and forecast system（ BJ-RUC） to study the influence of cloud droplets caused by aerosol pollution on the fine-scale numerical forecasting of summer precipitation in Beijing. The results show that the default concentration of cloud droplets in the BJ-RUC system is lower than the cloud droplet concentration calculated from the environmental model（ BJRUC-Nc case） whose prediction results is closer to the actual situation; aerosol increasing can increase or decrease precipitation.Specific displays：（1） Precipitation is mainly concentrated in the northeast region（ Pinggu,Miyun,Shunyi）,followed by the urban area, and the numerical model can better reflect the overall distribution and trend of precipitation in flood season of 2014;（2）BJ-RUC-Nc for light rain,moderate rain and heavy rain forecast is better than that of BJ-RUC,closer to the observations;（3） When the water vapor supply is insufficient（ insufficient）,it will promote（ suppress） the formation of precipitation particles, increase（ decrease） the precipitation efficiency,and increase（ decrease）the precipitation.