Use of a dual temperature-difference two-source model to estimate the turbulent energy fluxes under strongly advective conditions during BEAREX08

In-situ measurements of air temperature can be adversely impacted affected by non-ideal sensor placement and calibration errors while surface temperature is significantly influenced by atmospheric effects and variations in surface emissivity. Together these factors can result in significant uncertainty in the estimates of the surface-atmosphere temperature gradient that can substantially degrade the quality of the output from thermal remote sensing-based energy balance models. The Dual Temperature-Difference Two-Source (DTD) model was developed to minimize the uncertainty in the temperature gradient by using the double difference of the time rate of change in radiometric and air temperature observations. While the DTD model has been evaluated previously over a broad range of conditions, this study focused on quantifying the ability of the DTD model to correctly represent surface energy fluxes under strongly advective conditions using the ground-based radiometric temperature and meteorological observations collected during the 2008 Bushland Evapotranspiration and Agricultural Remote Sensing Experiment (BEAREX08). A comparison between the modeled and observed fluxes over irrigated and non-irrigated crops, as well as a natural grassland site, was conducted in order to study the impacts of advection and surface characteristics on the ability of the DTD model to reproduce the temporal pattern in the surface fluxes. The ability of the DTD model to accommodate errors in the surface-air temperature gradient for such an environment was also evaluated.