SATELLITE-DERIVED SURFACE TEMPERATURES WITH BOUNDARY-LAYER TEMPERATURES AND GEOSTROPHIC WINDS TO ESTIMATE SURFACE-ENERGY FLUXES

The surface sensible heat flux, H, and the latent heat flux, LE, were determined under unstable conditions for the First ISLSCP (Internation al Satellite Land Surface Climatology Project) Field Experiment (FIFE) site in eastern Kansas. NOAA 9 and 11 AVHRR radiative surface tempera tures, corrected for atmospheric effects using the split window techni que, were used for the surface temperature in a bulk atmospheric bound ary layer similarity formulation for H. Mean vertically integrated mix ed layer temperatures, determined from radiosonde data, were also requ ired in this technique. However, unlike previous applications, the pre sent approach avoids the need for direct wind speed measurements by us ing instead the geostrophic wind speed, V-G, as derived from the routi ne measurements of the surface pressure field. LE was then determined as the residual term of the surface energy balance, using H from the b ulk similarity formulation. Under the unstable conditions considered, results for both Hand LE were comparable to those found in previous wo rk by means of measured wind speeds with the same FIFE data. It is sho wn that for slight to moderate instabilities a 1% error in the frictio n velocity generally produces less than 1% error in H.