P1.2
Validation of daily global land surface albedo and anisotropy products from VIIRS
Miguel O. Román III, Graduate School of Arts and Sciences at Boston University, Boston, MA; and C. B. Schaaf, J. Liu, Y. Shuai, A. H. Strahler, C. K. Gatebe, and O. Coddington
A roadmap is presented for the validation of the proposed VIIRS daily albedo and anisotropy products by characterizing the surface anisotropy and capturing the daily temporal and spatial variations of surface albedos observed by measurements taken at multiple scales of resolution using field instruments, aircraft, and satellites. The NPP/NPOESS specification calling for a time-critical daily shortwave albedo product (at overpass time) represents a temporal improvement beyond that currently provided by EOS era algorithms and is driven by consideration of the surface energy budget variations possible from rapidly changing surface covers, e.g. burning, clearing, tilling, harvesting, and flooding. One of the primary challenges of this plan is to meet the temporal demands while still providing consistent high quality, high resolution, global surface albedo datasets over a sufficient period to constitute stable Earth Science Data Records (ESDRs), and Climate Data Records (CDRs) for the modeling and climate diagnostics communities. To assess the quality of these projected daily albedos, hourly measurements of surface albedos can be reconstructed from the Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo satellite product. These are compared with instantaneous ground data from field stations in the US. Qualitative intercomparisons between high-spatial resolution scenes derived from ASTER (15-m) and IKONOS (4-m) sensors and MODIS BRDF/albedo measurements (at 500-m) provide assessments of subpixel heterogeneity. This validation scheme not only relies on well calibrated global BSRN (Baseline Surface Radiation Network) and the US Surfrad (Surface Radiation Network) field data, but also includes aircraft-derived surface albedos as derived from the Solar Spectral Flux Radiometer (SSFR) measurements of upward and downward irradiance, and Cloud Absorption Radiometer (CAR) measurements of the bidirectional reflectance distribution function of various surface types. While VIIRS specifications require that the spatial coverage of the analysis will have to increase from the US to the entire globe, this effort will establish a protocol for post-launch validation efforts.
Poster Session 1, 4th NPOESS Symposium Poster Session
Tuesday, 22 January 2008, 9:45 AM-11:00 AM, Exhibit Hall B
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