Validating theoretical simulations of thermal emission hot spot effects on maize canopies

This is a development of some of our previous work on the analysis of thermal emission hot spot effects. In that work, which was a simulation study, a curve-fitting model was proposed to derive the hot spot amplitude and half width. Based on the curve-fitting model, a new algorithm that predicts the component temperature differences from the hot spot amplitude is presented. In this study, the objectives are to evaluate the accuracy of the curve-fitting model and the new prediction algorithm using both airborne measurements based on the wide-angle infrared dual-mode line/area array scanner (WiDAS) system and ground measurements. Based on a prior knowledge of crop structure parameters (e.g. the leaf area index (LAI), leaf angle distribution (LAD) and leaf dimensions), validation results indicate that the curve-fitting model and the prediction algorithm can accurately retrieve the hot spot amplitude and half width (R-2 > 0.90 and root mean square error (RMSE) < 0.15 K), and predict leaf and soil temperature differences from directional signals of both airborne and ground data (bias < 1 K). The error of prior knowledge can significantly affect the prediction accuracy of leaf temperature difference. Also discussed are the limitations of the model and future research and application.