Modeling gaseous dry deposition over regional scales with satellite observations—I. Model development

Surface spectral reflectances remotely sensed by environmental satellites were used to improve parametrization of surface processes 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.