Spatial-temporal Simulation Of PM_2.5 Concentration In Beijing-Tianjin-Hebei Area Based On Nonlinear Mixed-effects Model

In recent years,with the rapid development of China's social economy,human activities and nature will emit a large amount of pollutants,which has caused more and more atmospheric particulate matter in the atmosphere,and PM_2.5.5 not only has an important impact on air quality and visibility,It also poses a serious threat to the personal health of local residents.Due to the unique topography and climatic characteristics of the Beijing-Tianjin-Hebei region,it is difficult for air pollutants to migrate out and diffuse,resulting in a particularly serious PM_2.5.5 pollution in the Beijing-Tianjin-Hebei region.In order to gain a deeper understanding of the complex influence relationship between ground pollution source factors,meteorological conditions and atmospheric particulate matter concentration in the Beijing-Tianjin-Hebei region,and to reveal the temporal and spatial distribution of atmospheric PM_2.5.5 in the study area,this paper takes Beijing-Tianjin-Hebei as the study area,first using remote sensing inversion Sol-optical thickness?AOD?factor,meteorological factor,land use factor and PM_2.5concentration of near-surface layer were used as basic data to construct a mixed effect model.On this basis,two variables?square of atmospheric AOD data,AOD data?were introduced The product of the height of the boundary layer)established a nonlinear mixed effect model to further explore its relationship;for the lack of prediction results due to the non-randomness of the AOD data,the average PM_2.5measured on all available PM_2.5.5 monitoring stations for the day was introduced concentration,a second-stage model was established to fill it.Finally,the simulation results of the spatiotemporal variation of PM_2.5.5 concentration with the highest coverage,high temporal resolution?every day?,and spatial resolution of 10×10km were obtained.The research results show that the prediction accuracy of the first-stage nonlinear mixed model in the Beijing-Tianjin-Hebei region from 2013 to2016 is cross-validated,R2 is 0.79,086,0.84 and 0.85,RMSE and RPE are25.52?g/m³,32.19%,19.67?g/m³,26.26%,17.72?g/m³,27.93%and 16.85?g/m³,28.13%,greatly improving the simulation effect of regional PM_2.5.5 concentration.In addition,the statistics show that the number of grid cells filled by the second-stage model in 2013-2016 is 67612,66553,66001 and 66069 respectively,and the average predicted PM_2.5.5 concentration has been increased to 78.20?g/m³,66.66?g/m³ and54.44?g/m³ and 49.27?g/m³.The above research results show that the nonlinear mixed-effect model and the supplementary value can greatly improve the prediction accuracy of the model,and by introducing appropriate factors to improve the spatial prediction range of the model,it can effectively make up for the lack of data in the time and space of the ground monitoring station,and provide environmental protection for China.