Analysis of urban/rural spatial surface energy exchanges using a numerical model and satellite data

Current urban/rural surface energy balance simulations using boundary layer climate models have been found to be inaccurate, especially in modeled turbulent heat fluxes and surface longwave radiation. The weakness is primarily due to unreliable input data with regard to surface thermal and radiative properties utilized by the models. This study developed a new parameterization for evaluating regional surface moisture availability by use of concurrently-acquired satellite and surface meteorological measurements. The study also evaluated regional surface albedo using satellite data. Furthermore, a procedure was designed to integrate the satellite-derived surface parameters with a boundary layer climate model for simulating spatial surface energy exchange. The new parameterization and procedures were tested through spatial surface energy balance simulation of an urban/rural landscape in southeastern Nebraska. The modeled surface temperature and net radiation were compared to those derived from concurrent NOAA-AVHRR satellite data using comparative statistics and scatterplots. The errors in the modeled surface temperature were quite small, and were mainly attributed to errors in the estimation of surface moisture availability and satellite-derived surface radiant temperature. Modeled net radiation was also in good agreement with those calculated from satellite data. The errors in the modeled net radiation were due mainly to the simulated surface temperature and net longwave radiation. Modeled turbulent heat fluxes were in general agreement as compared to those reported in the literature, but the model tended to overestimate the latent heat flux for most rural land cover types. It was concluded that by incorporation of satellite-derived surface physical parameters into the boundary layer model, simulation on spatial surface energy exchange was much improved. The method and procedures developed from this study can be utilized in other urban/rural boundary layer models