Insights Into the Aerodynamic Versus Radiometric Surface Temperature Debate in Thermal-Based Evaporation Modeling

Mallick, Kaniska and Baldocchi, Dennis and Jarvis, Andrew and Hu, Tian and Trebs, Ivonne and Sulis, Mauro and Bhattarai, Nishan and Bossung, Christian and Eid, Yomna and Cleverly, Jamie and Beringer, Jason and Woodgate, William and Silberstein, Richard and Hinko-Najera, Nina and Meyer, Wayne S. and Ghent, Darren and Szantoi, Zoltan and Boulet, Gilles and Kustas, William P. (2022) Insights Into the Aerodynamic Versus Radiometric Surface Temperature Debate in Thermal-Based Evaporation Modeling. Geophysical Research Letters, 49 (15): e2021GL097. ISSN 0094-8276

Abstract

Global evaporation monitoring from Earth observation thermal infrared satellite missions is historically challenged due to the unavailability of any direct measurements of aerodynamic temperature. State-of-the-art one-source evaporation models use remotely sensed radiometric surface temperature as a substitute for the aerodynamic temperature and apply empirical corrections to accommodate for their inequality. This introduces substantial uncertainty in operational drought mapping over complex landscapes. By employing a non-parametric model, we show that evaporation can be directly retrieved from thermal satellite data without the need of any empirical correction. Independent evaluation of evaporation in a broad spectrum of biome and aridity yielded statistically significant results when compared with eddy covariance observations. While our simplified model provides a new perspective to advance spatio-temporal evaporation mapping from any thermal remote sensing mission, the direct retrieval of aerodynamic temperature also generates the highly required insight on the critical role of biophysical interactions in global evaporation research.