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

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

International Journal of Remote Sensing

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.