Monday, 10 January 2005
Multi-year Simulation of Surface Hydrological Components by Coupling Remote Sensing Data with Surface Observation
A model for parameterized subgrid-scale surface fluxes (PASS) has been proposed to use satellite data and routine surface observations to infer root-zone available moisture content and evapotranspiration rate with moderate spatial resolution. The PASS model has been applied within Walnut River Watershed in Kansas. Biweekly composite Normalized-difference vegetative index (NDVI) were collected from National Oceanic and Atmospheric Administration (NOAA) satellites. Local surface observations provided data on downwelling solar irradiance, air temperature, relative humidity, and wind speed. Surface parameters including roughness length, albedo, surface water conductance, and the ratio of soil heat flux to net radiation were estimated; pixel-specific near-surface meteorological conditions such as air temperature, vapor pressure, and wind speed were adjusted according to local surface forcing. The PASS modeling system makes effective use of satellite data and can be run for large areas for which flux data do not exist and where surface meteorological data are available from only a limited number of ground stations. Surface hydrological budget during a multi-year study was estimated by using radar-derived precipitation, surface meteorological observations, and satellite data. The modeled hydrological components in the Walnut River Watershed are evaluated with stream gauge data and with observed latent heat fluxes at available sites.