Satellite Aerosol Remote Sensing Data Assimilation And Observation System Simulation Experiment

Based on the new generation atmospheric chemistry model WRF-Chem and three-dimensional variational（3DVAR）assimilation method,aiming at the two processes of pollution in North China in January and October 2019,aerosol observations from Himawari-8（H-8）satellite aerosol optical depth（AOD）,surface PM monitors and CALIPSO extinction coefficient profiles were used for simulating the two cases.In addition,in order to evaluate the potential impact of the distribution of aerosol lidar observation networks on improving air quality prediction in China in the future,three groups of ground-based lidar observation networks are designed and the corresponding observation system simulation experiment（OSSE）is carried out.The simulation experiment in October 2019 shows that assimilating CALIPSO extinction coefficient makes the aerosol profile simulated by the model closer to the observation,and the aerosol spatial structure error is greatly reduced.Moreover,the prediction effect of PM₁₀,PM_2.5 and AOD has been significantly improved.The simulation results in January 2019 show that increasing the assimilation of AOD has little improvement on the effect of PM simulation,but it can effectively improve the vertical structure of atmospheric aerosol and make up for the limitations of traditional ground data in aerosol data assimilation.The OSSE experiment of aerosol lidar shows that the three-dimensional structure of aerosol can be simulated more accurately after assimilating the three-dimensional profile information of aerosol in the model.When the number of lidars increases from 0to 99 and 310,assimilation can significantly improve the three-dimensional aerosol analysis and prediction.However,when the number of radars increases from 310 to 590,the improvement effect of assimilation is very limited.The results show that the improvement effect of assimilation on aerosol prediction increases with the increase of the number of lidar.However,when the lidar reaches a certain number,the effect of assimilation on prediction improvement decreases gradually.