Modeling area-averaged fluxes over partially vegetated land surfaces using aircraft and in-situ thermal data

Abstract

A surface energy balance model is used in association with remotely sensed and in-situ data to examine issues of measurement, scaling, and aggregation of high frequency spatial variation in land surface properties and fluxes over regional scales. Results from this analysis show that instantaneous land surface fluxes modeled from high spatial resolution remotely sensed data may be estimated only approximately. Comparisons between modeled versus observed fluxes averaged over regional scales (roughly 225 square km), on the other hand, exhibit excellent agreement. Based on these results it is concluded that the estimation of surface fluxes at high spatial resolution is problematic because the remotely sensed measurements reflect local land surface conditions, while land surface fluxes are produced by processes associated with surface-atmosphere interactions occurring over substantially larger areas. Because land surface-atmosphere interactions effectively integrate high frequency spatial variance in land surface properties, relatively coarse spatial resolution (100s of meters - 1 km), or random samples of high resolution data, may be used for surface energy balance modeling over regional scales.