Land and Ocean Using SeaWiFS Measurements from 1997

15 Both sensor calibration and satellite retrieval algorithm play an important role in the ability to 16 determine accurately long-term trends from satellite data. Owing to the unprecedented 17 accuracy and long-term stability of its radiometric calibration, the SeaWiFS measurements 18 exhibit minimal uncertainty with respect to sensor calibration. In this study, we take 19 advantage of this well-calibrated set of measurements by applying a newly-developed aerosol 20 optical depth (AOD) retrieval algorithm over land and ocean to investigate the distribution of 21 AOD, and to identify emerging patterns and trends in global and regional aerosol loading 22 during its 13-year mission. Our results indicate that the averaged AOD trend over global 23 ocean is weakly positive from 1998 to 2010 and comparable to that observed by MODIS but 24 opposite in sign to that observed by AVHRR during overlapping years. On a smaller scale, 25 different trends are found for different regions. For example, large upward trends are found 26 over the Arabian Peninsula that indicate a strengthening of the seasonal cycle of dust emission 27 and transport processes over the whole region as well as over downwind oceanic regions. In 28 https://ntrs.nasa.gov/search.jsp?R=20120012819 2017-12-09T13:24:21+00:00Z