Conversion of radiometric to aerodynamic surface temperature with an anisothermal canopy model

Abstract

A land surface-atmosphere-radiometer model was applied to field data at the First International Satellite-Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE). The model converts from radiometric surface temperature taken at any zenith view angle to an equivalent isothermal (or aerodynamic) surface temperature. With data from one day at a grassy site with a leaf area index of 1.0, values of the three unknowns in the model, which describe the shape of the vertical foliage temperature profile, were found which best agree with reference radiometric and aerodynamic surface temperatures at the site. Having shown that the model can be optimized to be consistent with field data, the model was applied to data taken at the same site on the next day. In this case the model was not optimized but was used in a predictive mode to convert from a radiometric to an aerodynamic surface temperature. The aerodynamic temperatures predicted by the model were closer to the reference values (that is, estimates of aerodynamic temperature obtained by inverting Monin-Obukhov Similarity Theory) than were the radiometric surface temperatures in all cases, for an average improvement of 3.6 K.