Numerical Simulation And Characteristic Analysis Of A Haze Pollution Process In Beijing-Tianjin-Hebei Region

To investigate the pollution process from 2016.11.3 to 11.6 in Beijing,Tianjin and Hebei region,a simulations with anthropogenic emissions are conducted by using WRF-Chem V3.5?Weather Research and Forecasting Model coupled to Chemistry Version 3.5?.The effective simulated results shows that the atmospheric stability index can effectively quantify the atmospheric stable status in the process of pollution,both the K index and the TT index are more accurate than the other two indices.It is a powerful basis for discussing the causes of the occurrence and development of haze.There are three high value centers of pollution.They are Beijing Tianjin area,northeast Hebei and southern Hebei.The horizontal distribution of PM_2.5,PM₁₀ and SO₂ pollutants has a more obvious diurnal variation,while CO and NO₂ are not changed obviously.The pollution begin from 11.3 to the end of 11.6,all pollutants are obviously affected by the cold air except NO₂,and the concentration suddenly drops in 11.6.Most of the distribution of pollutants is limited to below 850hPa,and there is an obvious enrichment in the near surface layer,and the main distribution of NO₂ is the lowest,while the height of PM₁₀ and CO is the highest.Other main accumulation height of most pollutants is lower than that of PM₁₀.In addition to PM₁₀,there are two high-value centers of the other four pollutants,about 35°N and 38°N⁴0°N,that is southern Hebei,Beijing,Tianjin and northeastern Hebei.The pollution centers of PM₁₀ change several times during the whole process,which is obviously different from other pollutants.The analysis of backward trajectory tracking by Hysplit show that the pollution in Beijing and Tianjin is mainly derived from the external pollution of industry and transport in southern Hebei,while the pollution in the northeast of Hebei and southern Hebei is an endogenous pollution mainly affected by local emissions.With the classification of chemical composition,the main pollutants are CO,and with the classification of the particle size of the pollutants,the size of PM_2.5 and PM₁₀ are similar and their concentration is not very different,all of which have great contribution to the pollution.