Air Pollution Characteristics For Shenyang Using WRF-CMAQ

With the rapid development of industrialization and regional economy,air pollution has developed into a problem between more complex urban agglomerations.Based on the WRF-CMAQ model,this paper has established the Shenyang air quality model system,and analyzes the characteristics of the air pollution in Shenyang in the winter of 2017 based on the verification model operation results.Combined with the backward trajectory analysis model to explore the sources of regional pollutants transmission,the research results are as follows:（1）There is a high relative consistency between the simulated value and the actual monitored value in the trend of the meteorological parameter simulation results.The linear fitting correlation coefficient r of wind speed,wind direction,temperature,atmospheric pressure and humidity are 0.68,0.48,0.62,0.65,0.32,respectively.The chemical transport model has the same simulation result value for the concentration of each pollutant and the hourly concentration monitoring value.The linear correlation coefficient r of PM_2.5,PM₁₀,NOx,CO and SO₂ are 0.75,0.69,0.63,0.62,0.13,respectively.（2）The results of the local emission inventory calculation in Shenyang show that the PM_2.5,PM₁₀,SO₂,NOx,and CO emissions in the urban center are the highest,and the NH₃ emissions are high in the surrounding areas of the city.When the southwest wind prevailed in the ground in January2017,the concentration of PM_2.5,NO₂ and CO was higher.The concentration of PM₁₀ and SO₂ was higher when the northwest wind prevailed,while the north wind had a dilution effect on the concentration of each pollutant.（3）Contaminants are more likely to accumulate under the synoptic situation existing in high pressure,the higher humidity,the lower wind speed and inversion layer.The warm advection behind the front ridge of the high-altitude trough,topographic trough and Changbai Mountain Small High Pressure will also increase pollution of the regional air quality.（4）In 2017,the results of atmospheric trajectories in Shenyang city are mainly divided into four clusters.The highest SO₂ concentration in transport mode 1 in the northwestern direction is 38.29μg/m³,with the frequency of 30.91%.The transport mode2 in the northerly direction with the highest PM_2.5 and NO₂ concentration values of 90.47μg/m³,43.81μg/m³,the frequency of occurrence is 19.37%,the southerly transport mode 3 is cleaner,the proportion is 33.55%,and the PM₁₀ concentration value of transport mode 4 is99.83μg/m³,the transport accounted for 16.17%.Hebei Province,Shandong Province and Inner Mongolia Autonomous Region are the main external sources of PM₁₀ and PM_2.5 in Shenyang.The concentrations of PM₁₀ and PM_2.5 are more than 150μg/m³,75μg/m³respectively,while the sources of nitrogen and sulfide pollutants are mainly from local emission.