Comparison of FY-3A/MERSI, MODIS C5.1, C6 and AERONET aerosol optical depth in China

Obtaining accurate aerosol optical depth (AOD) information is important for climate change study and atmospheric environment monitoring. By using the method of band interpolation and temporal-spatial matching, the inversion accuracy of AOD products obtained from FY-3A/MERSI and from the C5.1 (Collections 5.1) and C6 (Collections 6) of Terra (Aqua)/MODIS are verified against AOD observations from AErosol RObotic NETwork (AERONET). Besides, the AOD distribution characteristics from the satellite observations for a case of dust weather and a case of severe haze occurred in China are analyzed. The results indicate that:(1) the inversion accuracy of FY-3A/MERSI is better (R=0.887, RMSE=0.234), but the values of AOD are generally smaller than observations of AERONET (Bias=-0.293); (2) with different underlying surfaces, the inversion accuracy varies between different satellite AOD products obtained from dark target algorithm (DT). The accuracy is higher where the vegetative cover is high, and lower in areas with small vegetation fractions. The inversion value is even missing over the so-called bright surface, where there is no vegetation cover; (3) MODIS C5.1 deep blue algorithm (DB) can retrieve AOD in areas of bright surface, but the effect is poor. In MODIS C6, the inversion accuracy in different underlying surfaces is better (RMSE:0.096-0.127); (4) among all the seasons, summer has the worst inversion accuracy, while the optimal accuracy may occur in any other seasons; (5) in the case of sand and dust storms, the monitoring effect of MODIS C6 AOD from DB is superior to other algorithms in western and northern regions of China, and the MERSI AOD distribution is discontinuous in this area. In general, MODIS C6 AOD distributes more continuously than MODIS C5.1 AOD. At the same time, the AOD value of MODIS 3 km is more accurate than other products. The conclusions above can provide references for the application of satellite AOD products in China.