A brief history of the thermal IR-based Two-Source Energy Balance (TSEB) model – diagnosing water and energy fluxes from plant to global scales

Authors: Anderson, Martha; Kustas, William - Bill; NORMAN, JOHN - University Of Wisconsin; DIAK, GEORGE - University Of Wisconsin; HAIN, CHRIS - Nasa Marshall Space Flight Center; Gao, Feng; YANG, YUN - Mississippi State University; Knipper, Kyle; XUE, JIE - Former ARS Employee; YANG, YANG - Beijing Normal University; Crow, Wade; HOLMES, THOMAS - Goddard Space Flight Center; NIETO, HECTOR - Spanish National Research Council; GUZINSKI, RADO - Spanish National Research Council; OTKIN, JASON - University Of Wisconsin; MECIKALSKI, JOHN - University Of Alabama; CAMMALLERI, CARMELO - University Of Milan; TORRES-RUA, ALFONSO - Utah State University; ZHAN, XIWU - National Oceanic & Atmospheric Administration (NOAA); FANG, LI - National Oceanic & Atmospheric Administration (NOAA); Colaizzi, Paul; AGAM, NURIT - Ben Gurion University Of Negev

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2024
Publication Date: 3/19/2024
Citation: Anderson, M.C., Kustas, W.P., Norman, J., Diak, G., Hain, C., Gao, F.N., Yang, Y., Knipper, K.R., Xue, J., Yang, Y., Crow, W.T., Holmes, T., Nieto, H., Guzinski, R., Otkin, J., Mecikalski, J., Cammalleri, C., Torres-Rua, A., Zhan, X., Fang, L., Colaizzi, P.D., Agam, N. 2024. A brief history of the thermal IR-based Two-Source Energy Balance (TSEB) model – diagnosing water and energy fluxes from plant to global scales. Agricultural and Forest Meteorology. 350. Article e109951. https://doi.org/10.1016/j.agrformet.2024.109951.
DOI: https://doi.org/10.1016/j.agrformet.2024.109951

Interpretive Summary: Geospatial maps of crop water use, or evapotranspiration (ET), using satellite imagery have a broad range of applications in agricultural water management and crop monitoring – particularly at spatial resolutions that can distinguish individual farm fields. Thermal infrared maps of land-surface temperature (LST) have demonstrated significant utility in mapping out ET variability down to meter scales, making use of the physical relationship between evaporative cooling and the temperature of the evaporating surface. However, LST data must be used with care to get good results, properly accounting for thermal sensor view angle and the mixture of soil and vegetation visible within the sensor field of view. The Two-Source Energy Balance (TSEB) model was developed specifically to address these issues, treating the temperature and evaporation from the soil and vegetation components separately. TSEB-based modeling systems have since been integrated into agricultural research and applications from field to global scales. This paper describes the challenges in thermal-based ET modeling leading to the TSEB development, as well as operational implementations for delivering TSEB-based ET and evaporative stress products over the U.S. and internationally in support of drought detection and water management.

Technical Abstract: Thermal infrared remote sensing of the land-surface temperature (LST) provides an invaluable diagnostic of surface fluxes and vegetation state, from plant and sub-field scales up to regional and global coverage. However, without proper consideration of the nuances of the remotely sensed LST signal, TIR imaging can give poor results for estimating sensible and latent heating {Hall, 1992 #238}. For example, sensor view angle, atmospheric impacts, and differential coupling of soil and canopy sub-pixel elements with the overlying atmosphere can affect use of satellite-based LST retrievals in land-surface modeling systems. A concerted effort to address the value and perceived shortcomings of TIR-based modeling culminated in the Workshop on Thermal Remote Sensing of the Energy and Water Balance over Vegetation in Conjunction with Other Sensors, held in La Londe les Maures, France in September of 1993 (Carlson, et al. 1995). One of the outcomes of this workshop was the Two-Source Energy Balance (TSEB) model (Norman, et al. 1995), which has fueled research and applications over a range in spatial scales. In this paper we provide some historical context for the development of TSEB and TSEB-based multi-scale modeling systems (ALEXI/DisALEXI) aimed at providing physically based, diagnostic estimates of latent heating (evapotranspiration, or ET, in mass units) and other surface energy fluxes. Applications for TSEB-based ET retrievals are discussed: in drought monitoring and yield estimation, water management, and data assimilation into – and assessment of – prognostic modeling systems. New research focuses on augmenting temporal sampling afforded in the thermal bands by integrating cloud-tolerant, microwave-based LST information, as well as evaluating the capabilities of TSEB for separating ET estimates into evaporation and transpiration components. While the TSEB has demonstrated promise in supplying water use and water stress information down to sub-field scales, improved operational capabilities may be best realized in conjunction with ensemble modeling systems such as OpenET (Melton, et al. 2022), which can effectively combine strengths of multiple ET retrieval approaches.