京津冀地区典型城市秋冬季PM_(2.5)输送特征研究

PM_(2.5)transport characteristics of typical cities in Beijing-Tianjin-Hebei Region in autumn and winter.

运用潜在源贡献分析(PSCF)方法,识别了2018年秋冬季京津冀地区典型城市北京,唐山和石家庄PM_(2.5)的潜在污染源区;基于气象-空气质量模式(WRF-CAMx)和传输通量计算方法定量评估了与其周边省市之间PM_(2.5)的传输贡献,识别了三个典型城市PM_(2.5)的传输路径,揭示了PM_(2.5)传输净通量的垂直分布特征.结果表明,三个城市秋冬季PSCF高值主要集中在河北南部,河南东北部和山西中东部地区;秋冬季PM_(2.5)均以本地贡献影响为主(51.78%~68.40%),外来贡献为辅(31.60%~48.22%),不同季节贡献率有所波动.整个观测期间,近地面主要表现为毗邻城市向北京和石家庄输送PM_(2.5),而唐山主要表现为向外输送PM_(2.5),净通量最大值出现在海拔0~50m,其净通量为-99.47t/d.同时鉴别出了一条主要的传输路径,即西南-东北方向.

The Potential Source Contribution Function(PSCF)method was applied to identify the potential pollution source areas of PM_(2.5)in three typical cities including Beijing,Tangshan and Shijiazhuang in autumn and winter of 2018.A meteorology-air quality coupling model system(WRF-CAMx)and the method of transport flux calculation were applied to investigate the transmission contribution of PM_(2.5)from the surrounding provinces,the transport pathway of PM_(2.5)in three typical cities and the vertical distribution characteristics of the net transmission flux of PM_(2.5).The results indicate that high values of PSCF in autumn and winter were mainly concentrated in the south of Hebei,the northeast of Henan and the central and eastern parts of Shanxi.Local emission sources were the predominant contributor(51.78%~68.40%)to PM_(2.5)in winter and autumn,followed by the external regions(31.60%~48.22%),and varied between two seasons.The contribution fluctuated in different seasons.The adjacent cities mainly export PM_(2.5)to Beijing and Shijiazhuang,and Tangshan mainly export PM_(2.5)to the adjacent cities,with the largest PM_(2.5)net fluxes mainly occurred at 0~50m,and the net fluxes value is-99.47t/d during the whole study period.Moreover,one important transport pathways were identified:the southwest-northeast pathway.