Scaling surface energy fluxes in a tall-grass prairie using large aperture scintillometer and MODIS data

Understanding the impact of spatial variability on the surface energy balance is of prime importance for many practical and theoretical considerations. Satellite remote sensing offers the advantage of capturing the spatial variability of many controlling parameters such as moisture and vegetation. However, until recently surface energy and mass fluxes derived from satellite sources are difficult to validate due to scale discrepancies between surface measurements and satellite resolutions. Measurements collected using a Large Aperture Scintillometer (LAS) over an annually burned tall-grass prairie in North-Central Kansas through the summer of 2005 are compared with surface energy fluxes derived from MODIS. Fluxes are derived from the MODIS sensor via coupling the vegetation and surface temperature with a soil-vegetation-atmosphere transfer (SVAT) scheme with an atmospheric boundary layer component. An eddy-covariance system is located between the transmitter and receiver of the LAS so we are able to scale from eddy-covariance footprint up to the satellite pixel resolution. Results indicate good agreement between the eddy-covariance and the LAS, as well as the LAS to satellite pixel. Implications focusing on the scaling of controlling parameters and relationship to resultant fluxes will be discussed.