Climate and Dynamics
Surface BRDF estimation from an aircraft compared to MODIS and ground estimates at the Southern Great Plains site
Article first published online: 21 OCT 2008
Copyright 2008 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 113, Issue D20, 27 October 2008
How to Cite
2008), Surface BRDF estimation from an aircraft compared to MODIS and ground estimates at the Southern Great Plains site, J. Geophys. Res., 113, D20105, doi:10.1029/2008JD010062., , , , and (
- Issue published online: 21 OCT 2008
- Article first published online: 21 OCT 2008
- Manuscript Accepted: 12 AUG 2008
- Manuscript Revised: 10 JUL 2008
- Manuscript Received: 4 MAR 2008
 Surface albedo, which quantifies the amount of solar radiation reflected by the ground, is an important component of climate models. However, it can be highly heterogeneous, so obtaining adequate measurements are challenging. Global measurements require orbital observations, such as those provided by the Moderate Resolution Imaging Spectroradiometer (MODIS). Satellites estimate the surface bidirectional reflectance distribution function (BRDF), a surface inherent optical property, by correcting observed radiances for atmospheric effects and accumulating measurements at many viewing and solar geometries. The BRDF is then used to estimate albedo, an apparent optical property utilized by climate models. Satellite observations are often validated with ground radiometer measurements. However, spatial and temporal sampling differences mean that direct comparisons are subject to substantial uncertainties. We attempt to bridge the resolution gap using an airborne radiometer, the Research Scanning Polarimeter (RSP). RSP was flown at low altitude in the vicinity of the Department of Energy's Southern Great Plains Central Facility (SGP CF) in Oklahoma during the Aerosol Lidar Validation Experiment (ALIVE) in September, 2005. The RSP's scanning radiometers estimate the BRDF in seconds, rather than days required by MODIS, and utilize the Ames Airborne Tracking Sunphotometer (AATS-14) for atmospheric correction. Our comparison indicates that surface albedo estimates from RSP and MODIS agree with Best Estimate Radiation Flux (BEFLUX) ground radiometer observations at the SGP CF. Since the RSP is an airborne prototype of the Aerosol Polarimetery Sensor (APS), due to be launched into orbit in 2009, these techniques could form the basis for routine BRDF validation.