Friday, 7 June 2002
Retrieval of surface BRDF parameters and albedo from the AVHRR pathfinder atmosphere dataset
The Advanced Very High Resolution Radiometer (AVHRR) Pathfinder Atmosphere (PATMOS) data set provides observations of Earth's reflectance for nearly twenty years (August 1981 through July 2001). This extraordinarily long period of observation allows the characterization of the Earth's surface reflectance properties through retrieval of the bi-directional reflectance distribution function (BRDF) and albedo. It is important to estimate the parameters of the Earth's energy balance from AVHRR to investigate the continuity between NOAA-series satellites and the NASA-EOS series (e.g. Terra). The surface information is retrieved from clear-sky reflectances for channels 1 and 2 of AVHRR by compiling numerous observations of the land from varying satellite view angles. This allows the retrieval of the BRDF parameters after atmospheric correction for molecular and aerosol extinction. The BRDF retrievals for the visible and near-IR channels allow the further estimation of a broadband albedo. Calculations are performed on a dataset with a nearly twenty year record, which not only provides information on albedo and possible changes over that time period, but also a substantial set of information as NOAA transitions from AVHRR to NPOESS/VIRS.
Supplementary URL: http://orbit-net.nesdis.noaa.gov/crad/sat/atm/aerosol/kknapp/