Sensitivity Analysis Of Parameters Of The Surface Meteorological Data And Topography Data In AERMOD Model

Atmospheric Environmental Impact Assessment is an important component of environmental impact assessment system,which is an influential environmental protection system.It provides a vital basis for determining the appropriateness of the proposed site and scale of the construction projects or planning projects by evaluating to what degree these projects impact the regional atmospheric environment after their completion.The basic prediction tool of atmospheric environmental impact is the atmospheric diffusion model,including the box-type model,Gaussian model,Lagrangian / Eulerian model,computational fluid dynamics model,and aerosol dynamics model.Currently,the mainstream international atmospheric dispersion models belong to the Gaussian model.Based on model ISC3,AERMOD(AERMIC Model)model was developed by the AMS / EPA Regulatory Model Improvement Committee AERMIC made up of U.S.Environmental Protection Agency and the American Meteorological Society.It is a steady-state plume dispersion model,which can simulate the short term(hourly average,daily average),long-term(annual average)concentrations distribution of the pollutants emitted from the point source,point source,and the body source according to the data of atmospheric diffusion boundary layer.This model takes into account the impact of the building wake,namely plume downwash,which is applicable to rural or urban areas,simple or complex terrain.In order to facilitate the understanding of the operation mechanism of the model,we briefly introduce the algorithm of AERMOD model,particularly focusing on the influence of surface meteorological parameters,high-altitude meteorological parameters and topographic parameters on AERMOD operation results.The parameter sensitivity analysis is divided into two steps: 1)to determine if the changes in the parameters will affect AERMOD model operation results.If so we will further analyze its sensitivity.If not,we will ignore them in the follow-up research;2)to use One way ANOVA analysis to further study the sensitivity of these parameters and put them in the order.The results show that,among parameters including wind direction,wind speed,time,total cloud cover,wet bulb temperature,low cloud cover,rainfall,dry bulb temperature,precipitation type,relative humidity,sea level pressure,dew point temperature,the surface pressure only the wind direction,wind speed,site pressure,cloudiness,and the dry bulb temperature will affect the model operation results without considering settlement factors.The parameter sensitivity order is like this: wind speed>cloud amount > temperature>site pressure.Terrain parameters(reflectivity,Bonn,roughness)have great impact on the result of the operation and therefore when determining the parameter values,we should be science-based and resort to relevant certification authorities.Different land use types also have considerable impact on the diffusion of pollutants concentration.Under the same conditions,different surface pollutant concentrations are ordered like this: First,the dry climate: the surface of the water,grassland and farmland,cities,deserts,wetlands,deciduous forest,coniferous forest.Second,moderate humidity climate: the surface of the water,grassland,desert,farmland and city,deciduous forest,coniferous forest,wetlands.Third,The humid climate: desert,city and coniferous forest,water,arable land,grassland,wetland,deciduous forest.This study will help the environmental assessment workers screen and optimize the relevant parameters under the existing meteorological data and surface data,estimate the potential error,so that the atmospheric prediction in the environmental assessment is of more practical significance.