Simultaneous estimation of surface photosynthetically active radiation and albedo from GOES

A previous algorithm developed to estimate photosynthetically active radiation (PAR) from satellite observations is improved and extended to retrieve surface albedo as well. The revised algorithm was validated with GOES-12 data over the North America continent. We used measurements from six SURFRAD and six FLUXNET sites in 2003 to validate the GOES PAR and albedo retrievals. The results show that GOES instantaneous PAR retrievals have a mean deviation of 175.0 mu mol s^-1 m^-2 (20.4% in relative value), a bias of 15.4 mu mol s^-1 m^-2 (2.0% in relative value), and a correlation coefficient of 0.881 for the sites under all-sky conditions. GOES daytime averaged PAR has a mean deviation of 91.3 NASA mol s^-1 m^-2 (11.8% in relative value), a bias of 14.1 mu mol s^-1 m^-2 (2.0% in relative value), and a correlation coefficient of 0.931 for all the sites under all sky conditions. Compared with the albedo measurements at the six FLUXNET sites, GOES albedo retrievals in 0.4-0.7 mum have a mean deviation of 0.017, a bias of 0.002 and a correlation coefficient of 0.773, while the corresponding MODIS visible albedo product has a mean deviation of 0.021, a bias of -0.028 and a correlation coefficient of 0.600.