Estimation of crop gross primary production ( GPP ) : fAPARchl versus MOD 15 A 2 FPAR

a Universities Space Research Association, Columbia, MD 21044, USA b Biospheric Sciences Laboratory, National Aeronautics and Space Administration/Goddard Space Flight Center, Greenbelt, MD 20771, USA c Sigma Space Corporation, Lanham, MD 20706, USA d Climate and Radiation Laboratory, Code 613, National Aeronautics and Space Administration Goddard Space Flight Center, Greenbelt, MD 20771, USA e Goddard Earth Sciences and Technology Center, University of Maryland Baltimore County, Baltimore, MD 21228, USA f Hydrology and Remote Sensing Laboratory, Agricultural Research Service, US Department of Agriculture, Beltsville, MD 20705, USA g School of Natural Resources, University of Nebraska—Lincoln, Lincoln, NE 68588, USA