Numerical Prediction System Of Air Quality In Shanxi Province

As an important energy and heavy chemical industry base in China,Shanxi have been experiencing hazardous level of air pollution with the economic expansion and rapid urbanisation growth.The present mainstream model of numerical prediction of air quality and numerical simulation of air pollutants is WRF-CHEM coupling model.In this paper,based on WRF-CHEM couplind model,an air quality numerical forecasting system suitable for the complex underlying surface conditions in Shanxi has been established to provide the obejective concentration prediction of typical air pollutants with high spatial and temporal resolution.The high-resolution numerical model of air quality has been developed.Firstly,the nested grid settings and vertical layering scheme for the model system wereidentified.Secondly,the main physical process parameterization schemes were confirmed,such as Noah land surface process coupled with UCM.Finally the major chemical process options were detrermined.A list of high-resolution anthropogenic emission sources in Shanxi has been improved.Based on MEIC V1.0 emission data,according to the chemical mechanism and model simulated area,the emission source files were established,which also considered the diurnal variation factor.At the same time,the first source emission intensity of typical air pollutants,such as PM2.5and SO2,was analyzed.The optimization of PBL scheme suitable for the complex underlying surface was carried out.Surface meteorological elements,PM2.5concentration,dynamic and thermal PBL stratification were simulated in the typical winter stable weather condition of Shanxi province.The effects of PBL thermal stratification and turbulent transportation differences on PM2.5concentration were discussed.The results indicated that surface meteorological elments and PM2.5concentration showed less error,and more close to the observations.The differences of PBL thermal stratification(at night),turbulent transportation and surface wind speed(in the afternoon)simulated by different PBL shemes led to the differences of surface PM2.5concentration.The warm start technology of atmospheric chemical coupling model has been studied,and the effect of warm start on the initial field and forecast results was analyzed.The results showed that model could better reflect the distribution characteristics of air pollutants concentration at the initaial time by updating the initail concentration value,and the prediction ability of surface pollutants concentration for 12 h could been significantly improved.The framework for environmental air quality forecasting system has been established facing business applications.The real-time operation of model system on High Performance Computer has been realized,and the objective products of high temporal-spatial resolution specific pollutants' concentration were provided to meet business requirements.The numerical and grade tests have been carried out,and the prediction ability and possible deviation sources of the model system were analyzed.