Improving Retrieval Accuracy for Aerosol Optical Depth by Fusion of Modis and Caliop Data

Original scientific paper MODIS and CALIOP are two independent observation instruments in the A-train satellite constellation. They both provide aerosol optical depth (AOD) retrievals and scan the same points on the Earth’s surface within a two-minute interval. With different design principles, MODIS and CALIOP instruments obtain varying AOD retrieval accuracies under different conditions. In this paper, we propose a two-stage fusion approach, including an analysis stage and an integration stage, to improve AOD retrieval accuracy. In the analysis stage, we systematically analyse conditions where MODIS retrieves well while CALIOP does not, and vice-versa. In the integration stage, we combine AOD retrievals from both instruments together by drawing on the other's strong points to make up one's weak points. We test the fusion approach on the two-year collocated data from MODIS, CALIOP and AERONET. The fusion result is significantly more accurate than AOD retrievals from any single observation facility.