MODELING GASEOUS DRY DEPOSITION OVER REGIONAL SCALES WITH SATELLITE-OBSERVATIONS .1. MODEL DEVELOPMENT

Surface spectral reflectances remotely sensed by environmental satellites were used to improve parametrization of surface process in modeling dry deposition over large geographic regions. A coupled reflectance-resistance model was developed for deriving canopy parameters such as leaf area index (LAI) from spectral radiances reflected from a canopy-soil system and for estimating canopy conductances that control pollutant transfer to various sinks inside a plant canopy. The new model was tested with local-scale measurements of ozone dry deposition to a tallgrass prairie along with remote sensing data from SPOT 1 and Landsat 5 extracted for the field measurement site. The model driven by satellite observations closely described both seasonal and short-term changes in canopy total green LAI. Ozone canopy stomatal conductances and dry deposition velocities modeled with satellite-derived LAI agreed with measurements with root mean square differences of 0.12 and 0.11 cm s-1, respectively.