A Simulation Study On Aerosol Distributions And Optical Depth Over China And The Globe

The Model of Atmospheric Transport and Chemistry (MATCH) is used to simulate the spatial distribution and seasonal variation of AOD (Aerosol Optical Depth) and five types aerosols, by taking NCEP/NCAR reanalysis data and CAM3 model results as its meteorological input. The AOD obtained by MATCH is then compared with the MODIS (MODerate resolution Imaging Spectro-radiometer) satellite data, the CSHNET (the Chinese Sun Hazemeter Network) and the AERONET observational data. The comparison of the results in this work with MOD08_M3 indicates that MATCH has the basic ability to simulate the AOD variability over China region. The correlation coefficient between the simulation with MOD08_M3 data and CSHNET observational data are 0.51 and 0.79 (both withα< 0.0001) respectively. By taking NCEP/NCAR reanalysis data in 2006 as model driving field, the simulated results show that the AOD over China varies greatly with different regions and seasons. The higher value of AOD occurred in Sichuan Basin, North China, Central China and South China, whereas the lower values of AOD are mainly located in Northwest China, Northeast China and Tibetan Plateau. The AOD over China is mainly generated by sulfate aerosol, secondly by organic aerosol and soil dust aerosol, and the least by black carbon and sea-salt aerosol. The composition of aerosol in Central China is similar to that in North China. The AOD of these two regions are higher than other regions and both are mainly caused by sulfate aerosol. The composition of aerosol in South China is similar to that in Southwest China. The AOD in these two regions are mainly contributed by sulfate, organic and black carbon aerosol, in which sulfate aerosol can contribute as much as 60%. The AOD caused by these three aerosol types change little in January, April and October and is relatively lower in July due to the removal effect of precipitation. The AOD in Northwest China caused by soil dust aerosol takes up greater proportion particularly in April. The lower AOD values in January, July and October there show that the air quality in Northwest China is better than that in other regions. AOD values of Northwest China and Tibetan Plateau are less than the averaged level over China in 2006.The Climate-Aerosol model system (CAM3-MATCH) is designed to study the impacts of anthropogenic aerosols on the global environment, based on the Community Atmosphere Model 3(CAM3) and MATCH. Taking climate data of 2001 as meteorological driver, this simulation indicate that the high concentration areas of sulfate, black-carbon and organic carbon are mainly located in North America, Europe and East Asia. Higher sea-salt concentrations are generally associated with sea areas with stronger surface winds. The major centers with high concentration of dust aerosol are located over Sahara, Southern Africa, the southern part of Latin America and Middle Asia respectively. There are strong seasonal cycles in the five species of aerosols. The results of this work are consistent with AeroCom, which indicates that the system built in this work is appropriate to simulate the five species of aerosols and their seasonal variations. This work lays a foundation for the online running of these two models and simulation of aerosol radiative forcing and aerosol effects on climate.