Analsis of historical AVHRR PATMOS aerosol data in support of the long-term trend study

The long-term trend of aerosol optical thickness (AOT) over the global oceans has been studied by using a nearly 25-year aerosol record from the Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Atmosphere (PATMOS) climate data. Both global and regional analyses have been performed to derive the AOT tendencies for monthly, seasonal, and annual mean AOT values at AVHRR 0.63mum channel (or Channel-1). A linear decadal change of -0.01 is obtained for globally and monthly averaged aerosol optical thicknesses of AVHRR Channel-1. Sensitivity analyses have also been performed to study the effects of radiance calibration and aerosol retrieval algorithm on the global aerosol long-term tendencies.