The Temporal And Spatial Distribution Characteristics Of Aerosols In The Bohai Rim

Atmospheric aerosol is an important part of the earth atmosphere radiation balance.With the change of time and space,its particle size and optical characteristic distribution show variability and non-uniformity.It is an important topic in the study of global climate change and numerical simulation.The aerosol optical properties of Xianghe station(suburb),Beijing station(urban area),Xinglong Station(forest area)and Binhai New Area Station(coastal area)in the Bohai Sea area are studied by using the aerosol optical depth(AOD)data measured by the global data observation network and the hand-held sun photometer.The aerosol optical depth in summer is the highest in all stations,and the wavelength index season is the highest.The changes of the nodes were summer>autumn>w:inter>spring,mainly between 0.7-1.5.In the seasonal variation of turbidity coefficient,summer is the highest,spring is the second,autumn and winter are at a lower level,and the air in Beijing,Xianghe and Binhai New Area is mainly turbid.In the aerosol classification,the fine growth mode is the main control mode in the high and low value areas of four stations,and only in Beijing,Xianghe and Xinglong low value areas in spring is jointly controlled by the coarse growth mode and the fine growth mode.Compared with the observation data of solar photometer,the accuracy of MODIS C6.1 aerosol optical depth product data are confirmed,and the new fusion data suitable for Bohai Sea area is optimized.Using the new fusion data from January 2009 to December 2018,the spatial and temporal distribution and change characteristics of the study area are calculated.According to the spatial distribution and time series changes of monthly AOD,there are two high value months in February which are prone to sandstorm and haze,and in June which are in the same period of rain and heat;in the seasonal analysis,the regional average summer shows the highest value(0.433),and the autumn shows the lowest value(0.275);the interannual variation shows that the AOD in 99.8%of the region around the Bohai Sea shows a decreasing trend,and the weak decreasing region accounts for the majority The measure of area.The spatial distribution shows that the aerosol optical depth is low in the northwest and high in the southeast.Based on the wavelength index data of MODIS C6.1,the temporal and spatial distribution characteristics of aerosol particle size in the study area are calculated.In the characteristics of monthly variation,the wavelength index of the whole region in March is the lowest in the whole year,with a value of 1.158.In July,the median value is the largest in the whole year,with a value of 1.562.In the seasonal characteristics,the wave length index of the whole region in summer is higher than that in other seasons,with a value of 1.5-1.7.In autumn,it is significantly lower than that in summer,Most of the values are in the range of 1.4-1.5.In winter,the wavelength index is the lowest in four seasons,only 1.3-1.4.In the interannual variation,the wavelength index of 99.53%increased,the fine particles decreased,the coarse particles increased.In the spatial distribution of wave length index around Bohai Sea,the overall range value is 1.1-1.6,which is dominated by man-made fine-grained aerosols.