Utility of a Thermal-based Two-source Energy Balance Model for Estimating Surface Fluxes over Complex Landscapes

Many landscapes are comprised of a variety of vegetation types with different canopy structure, rooting depth, physiological characteristics, including response to environmental stressors, etc. Even in agricultural regions, different management practices, including crop rotations, irrigation scheduling, planting density, seed varieties, and other factors result in complex patterns in vegetation growth stages, canopy cover, canopy architecture and cropping densities. This variability at the canopy, field and landscape scale, makes it very challenging for quantifying spatially-distributed surface fluxes. This paper describes a robust but relatively simple thermal-based energy balance model that parameterizes the key soil/substrate and vegetation exchange processes affecting the radiative balance and turbulent energy transport with the overlying atmosphere. The thermal-based model, called the Two-Source Energy Balance (TSEB) model solves for the soil/substrate and canopy temperatures that achieves a balance in the radiation and turbulent heat flux exchange with the lower atmosphere for the soil/substrate and vegetation elements. The TSEB scheme permits interaction between soil/substrate and canopy elements which are both coupled to the atmosphere via the canopy-air temperature; this canopy-air temperature is highly correlated to the aerodynamic surface temperature used in computing surface sensible heat flux. As a result, the TSEB modeling framework is applicable to a wide range of atmospheric and canopy cover conditions. An overview of recent applications of the TSEB modeling framework to a variety of agricultural landscapes is presented.