摘要:利用地面细颗粒物（PM2.5）浓度和气象常规观测资料、地基 AERONET观测资料、GFED生物质燃烧排放清单和大气化学—天气耦合模式WRF-Chem，模拟研究了华北地区2014年10月气象要素和大气污染物的时空演变，重点关注北京10月7～11日的一次重霾事件及其天气形势、边界层气象特征、输送路径、PM2.5及其化学成分浓度变化等特征，以及秸秆燃烧对华北和北京地区细颗粒物浓度和地面短波辐射的影响。与观测资料的对比结果显示，模式可以很好地模拟北京地区地面气象要素和PM2.5质量浓度，考虑秸秆燃烧排放源可以明显改进北京PM2.5浓度模拟的准确性，但在重度污染情况下，模式总体上低估气溶胶光学厚度和高估地面短波辐射。10月7～11日北京地区重霾事件主要是不利气象条件下人为污染物累积和区域输送造成，也受到华北地区南部秸秆燃烧的影响。河南北部、河北南部和山东西部大面积秸秆燃烧释放的气态污染物和颗粒物在南风的作用下输送至北京，秸秆燃烧对北京地区地面PM2.5、有机碳（OC）、硝酸盐、铵盐、硫酸盐和黑碳（BC）的平均贡献率分别为24.6%、36.8%、23.2%、22.6%、7.1%和19.8%，秸秆燃烧产生的气溶胶可以导致北京地面平均短波辐射最大减小超过20 W m－2，约占总气溶胶导致地表短波辐射变化的24%。
关键词:秸秆燃烧/
GFED生物质燃烧排放清单/
WRF-Chem模式/
细颗粒物(PM2.5)/
气溶胶化学组分/
短波辐射
Abstract:Open biomass burning is one of the important sources of particulate matter (PM) and gaseous species at the global scale, whereas crop residual burning is the fundamental way of biomass burning in East China. By using surface observations of air quality and meteorological variables, aerosol optical depth (AOD) data from Aerosol Robotic Network (AERONET), biomass burning emission from Global Fire Emissions Database (GFED) inventory, and the Weather Research and Forecasting model with Chemistry (WRF-Chem), this study investigated the evolution of air pollutants in the Huabei Plain in October 2014, focusing on a severe haze event in Beijing in 7-11 October. The synoptic condition, boundary layer meteorology, transport pathway, spatial-temporal distribution of aerosol chemical components in PM2.5, and the impact of crop residual burning on fine particle concentration and surface shortwave radiation during this period were analyzed. The model well reproduces the surface meteorological variables and PM2.5 concentrations but underpredicts the AOD and overpredicts the surface shortwave radiation during haze days. Notably, the model simulation of PM2.5 concentration substantially improved by considering crop residual burning emission. The severe haze event in 7-11 October in Beijing was mainly caused by the accumulation and regional transport of air pollutants under stable atmospheric condition and was also affected by the northward transport of air pollutants produced by crop residual fires over the wide areas of southern Hebei, northern Henan, and western Shandong province. The model simulation revealed a considerable influence of crop fire on the surface aerosols in Beijing, with the percentage contributions of 24.6%, 36.8%, 23.2%, 22.6%, 7.1%, and 19.8% for PM2.5, organic carbon (OC), nitrate, ammonium, sulfate, and black carbon (BC) concentrations, respectively. The mean reduction in the surface shortwave radiation in Beijing induced by aerosols from crop fire exceeded 20 W m?2, accounting for approximately 24% of the changes in shortwave radiation by all aerosols.
Key words:Crop residue burning/
Global fire emissions database/
WRF-Chem model/
Particulate matter (PM2.5)/
Aerosol chemical component/
Shortwave radiation
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