Spatial And Temporal Distribution Characteristics,Simulation And Observation Research Of HCHO And NO₂ In China

In recent years,ozone pollution has become one of the main problems of air pollution in China.The main components of ozone precursors are VOCs and NO_x.The representative species HCHO and NO₂ play an important role in the photochemical reaction.In this paper,the QA4ECV data set and the tropospheric vertical column density（VCD）products released by Sentinel-5P/TROPOMI and the atmospheric chemical model WRF-Chem are used to study the spatial and temporal distribution characteristics,simulation,and observation of HCHO and NO₂ in China.The research content and conclusions are mainly divided into three parts:1.By collating the QA4ECV data set and the Sentinel-5P/TROPOMI satellite product release,it is concluded that HCHO and NO₂ tropospheric VCDs are higher in economically developed areas such as Beijing,Tianjin and Hebei,the Yangtze River Delta,and the Pearl River Delta.From 2010 to 2013,it increased slightly,and then decreased slightly and stabilized.HCHO was significantly higher in summer than in other seasons,and NO₂ was highest in winter.In terms of changes in the ozone generation control area,after 2013,the VOCs pollution control area in Beijing-Tianjin-Hebei,the Yangtze River Delta and its surrounding areas is decreasing,and the VOCs-NO_x cooperative control area is increasing.2.Through WRF-Chem simulation of a case of ozone pollution that occurred in central and eastern China in early June 2018.The simulated HCHO and NO₂ tropospheric VCD and TROPOMI satellite products have good consistency,but they are lower than satellite observations.On the ground,most of the high-value areas of NO₂ and HCHO correspond to high-value areas of ozone concentration,and high NO₂ concentrations in the early morning and morning correspond to high ozone concentrations in the afternoon and evening;the chemical initial field and boundary conditions in the WRF-Chem simulation Sensitivity tests were carried out.The three schemes were:MOZART-4,CAM-Chem,and no input.The tropospheric nitrogen dioxide vertical column concentration had little difference in simulation results;the tropospheric formaldehyde vertical column concentration and near-surface ozone The simulation results of the three schemes are quite different.Among them,the ozone simulation value of the CAM-Chem scheme is slightly lower than that of the MOZART-4 scheme.The agreement between the two and the ground monitoring varies in different regions and times,and ozone appears.The time when the concentration maximum value is input to MOZART-4 is closer to the ground monitoring,and the other time is CAM-Chem to be closer to the ground monitoring..3.This study used TROPOMI primary data and other auxiliary data,and conducted a formaldehyde vertical column concentration inversion test using the classic DOAS method.It can be concluded that the inversion results have certain correlation with satellite secondary products.