Research On The Interaction Of Aerosol-meteorological Elements Based On Aerosol Data Assimilation

Meteorology and aerosol influence each other in the atmosphere.With the continuous strengthening of pollution reduction and the reduction of extreme pollution incidents in winter,more and more attention have been paid on autumn air pollution incidents.In order to better carry out the study of meteorological and aerosol models in China,the Weather Research and Forecasting model coupled to Chemistry(WRF-Chem)and the Grid Statistical Interpolation(GSI)three-dimensional variation(3DVAR)data assimilation(DA)System were used in this paper.We selected a pollution process in autumn,and carried out the following research contents:(1)Using WRF-Chem to couple MOSAIC mechanism and GOCART mechanism respectively,an experiment was carried out on a case in autumn over most of China.WRF-Chem model can better simulate the weather conditions,but the accuracy of PM_2.5concentration simulation is affected by the uncertainty of the emission inventory;The GOCART aerosol mechanism is effective for PM₁₀and dust in northwest regions,and sea salt in coastal areas.The MOSAIC aerosol mechanism has a better simulation of the concentration of PM_2.5and gas pollutants in the central and eastern regions.(2)Based on the WRF-Chem coupling MOSAIC mechanism,GSI was used to further carry out the autumn aerosol-meteorological data joint assimilation research.After assimilation of PM_2.5,there exits underestimates caused by the lack of emission sources in northwest has been better improved,and the overestimation in North China Plain and the Yangtze River Delta has been reduced.The correlation between the model simulation and the observations is significantly improved;The assimilation of meteorological data can effectively correct the PM_2.5peak-clearing process simulation delay or peak shift caused by the inaccurate simulation of meteorological conditions;On the basis of PM_2.5assimilation,meteorological conditions changed by data assimilation have a more accurate expression of the influence of changes in PM_2.5concentration.The influence of meteorology on PM_2.5concentration is related to the concentration.The higher the PM_2.5concentration,the greater the impact.(3)Based on the results of the joint assimilation test,a 48-hour forecast comparison test was designed to explore the mechanism of the interaction between the meteorology and aerosol.The feedback effect of aerosol-radiation leads to the decrease of T₂,the increase of RH₂,and the decrease of PBLH.The increase of RH₂leads to the enhancement of the heterogeneous process related to humidity,which leads to the increase of the concentration of nitrate,ammonium and sulfate.And the increase in PM_2.5concentration in turn reduce the radiation reaching the ground.