北京不同区域气溶胶辐射效应

Radiative Effects of Aerosols in Different Areas of Beijing

采用大气辐射传输模式SES2以及2013年1月—2015年10月欧洲中期天气预报中心细网格再分析资料计算了北京地区4个观测站地面接收的短波辐射通量,分析了晴天和云天北京城郊气溶胶对总辐射的定量影响时空变化特征。结果表明:北京城区和近郊区气溶胶对总辐射的影响约为远郊区的2倍,北京南部和西部气溶胶对辐射的影响较大,晴天和云天北京城区和近郊区气溶胶对总辐射的削减值分别为146.23～180.99 W·m^(-2)和202.11～217.02 W·m^(-2),晴天总辐射削减空间差异较大;秋冬季气溶胶对总辐射的影响明显大于春夏季,北京市观象台秋冬季气溶胶对总辐射的削减作用最大可达60%,较春夏季高10%～20%;北京城郊总辐射和直接辐射削减率与气溶胶光学厚度变化均呈线性关系,近地面PM_(2.5)浓度对辐射的影响不容忽视。

Shortwave radiation fluxes on the ground at four stations in Beijing are calculated using the second Sun-Edward-Slingo radiative transfer（SES2） model and cloud and vapor data from European Centre for Medium-Range Weather Forecasts reanalysis dataset（ECMWF-thin） with 0. 125° X0. 125°spatial resolution from January 2013 to October 2015. And impacts of aerosol on surface radiation on synoptic scale in clear-sky and cloudy days in the urban and suburb of Beijing are respectively analyzed based on the difference between the modeled global horizontal irradiances（GHI） with the inclusion of cloud and vapor and the corresponding observations. Spatial-temporal variation characteristics of quantificational aerosol radiative effects on the synoptic scale in the urban（polluted area） and at Shangdianzi Regional Background Station（clean area） are preliminarily studied in different haze pollution episodes. Quantitative models between deduction ratios of GHI caused by aerosol and PM_（10） and PM_（2.5） concentrations in the urban and suburb of Beijing are established. Results show that aerosol radiative effects on the synoptic scale in the urban are about twice of that at Shangdianzi Station, and those in south and west are larger than other areas.GHI reductions caused by aerosol fall in 146. 23 — 180. 99 W · m^（-2） in clear-sky days and 202. 11 —217. 02 W · m^（-2） in cloudy days, and differences of GHI deduction in different districts in clear sky are larger than those in cloudy days. Aerosol radiative effects on the synoptic scale in autumn and winter when concentrations of PM_（10） and PM_（2.5） are higher in the same period are obviously lager than those in spring and summer. Reduction ratios of GHI in southern suburbs of Beijing in autumn and winter are 10% —20 %higher than those in spring and summer during 2013 — 2015. Linear relationship between reduction ratios of GHI and direct radiation（DIR） and AOD in the urban and suburb of Beijing are found and impacts of AOD on DIR are larger than GHI, especially in the urban with heavy haze. Additionally, impacts of PM_（2.5） concentration on GHI and DIR cannot be ignored. Results above have certain scientific and practical application values for better understanding the interaction between aerosol and meteorological conditions such as solar radiation, and improvements of refined assessments and forecasts of solar energy resources.