Integrated Analysis on Spatial Distribution Characteristics of PM₁₀ Concentration Based on Variational Processing Method in Beijing

A study is carried out on the spatial distribution characteristics of PM₁₀ mass concentration and effect of pollutants from motor vehicle emissions in the main streets, the ring roads which are located in urban districts and suburbs in Beijing, based on the integrated Atmospheric Pollution Field Experiments (BECAPEX, Beijing City Atmospheric Pollution Experiment) and variational processing methods by satellite retrieval data whose horizontal resolution is 1 km. The results show that PM₁₀ mass concentration in the majority of urban area are low, especially in ancient building communities which are located inside the Second Ring Road and in large afforestation zone. High concentration areas of PM₁₀ in suburb distribute along ring roads, and pollutions are much serious in the southwest, the south and the northeast of the suburbs. The above mentioned fact shows that the impact of vehicle emissions on PM₁₀ concentration is very serious in blocks which are located in urban districts and suburbs. Before satellite retrieval data are corrected by variational processing method, the value of MODIS AOD (Aerosol Optical Depth) in urban districts and suburbs are much higher than that in exurb, there are inveracious high value areas of AOD in its spatial distribution field and its unsymmetrical spatial distribution characteristics is not obvious. AOD values in most exurbs are lower than that in urban districts and suburbs, especially in the northwest of the exurb. But AOD values in the southwest and the southeast of the exurb are relatively high. The remarkable corrected effect is obtained by using a point plane integrated observation research technique and variational processing method by MODIS AOD retrieval data and corresponding observation data on the ground. AOD variational field with higher resolution information could be used to describe unsymmetrical spatial distribution characteristics in urban district and suburb detailedly, especially in exurb. This method can be used to make up the limitation of observation in exurbs. After satellite retrieval data are corrected by variational processing method, unsymmetrical spatial distribution char acteristics of AOD value are more distinct and conformed with that of PM₁₀ concentration. Inveracious high value areas of AOD distribution are removed. Orbicular distribution of AOD in near suburb is more obvious and its unsymmetrical distribution characteristics in exurbs are also more notable. The location and intensity of the above high and low AOD value areas are stable accordingly.