Spatial and Seasonal Variations of Surface PM10 Concentration and MODIS Aerosol Optical Depth over China

We examine the spatial and temporal variabilities of ground-observed concentrations of particulate matter with diameters <= 10 mu m (PM10) over China and compare them with satellite-retrieved data on the aerosol optical depth (AOD) collected over the period 2003-2005 using a moderate resolution imaging spectroradiometer ( MODIS). Annual mean values of the PM10 concentrations and AOD show a strong spatial correlation, indicating the consistent presence of aerosol concentrations. However, the temporal correlation between the monthly values of the PM10 concentrations and AOD indicates a regional contrast in their seasonality. The correlation coefficients are 0.6 or higher in the southeastern coast region, whereas they are -0.6 or lower in the north-central region. The regional discrepancy is most likely due to the difference in the size distributions of aerosols. This is also supported by the data on the distribution of the Angstrom exponent and fine mode fraction obtained from the MODIS. The characteristics of the aerosols with respect to coarse and fine particles are discussed in this study.