## 1 Introduction
Temperature gradients in the planetary boundary layer influence the rate of evaporation, and changes in surface roughness occur as soil moisture decreases and vegetation wilt, further affecting the exchange of moisture between the surface and the atmosphere. Though these models have made ET determination easier are more flexible in time and scale. With their generic settings, they have been applied over large continents in recent years such as Water Productivity Open-access portal version 2 (WaPORII) for Africa, the Global Daily Evapotranspiration Portal-Atmosphere-Land Exchange Inverse algorithm (GLODET-ALEXI) for the Mediterranean region, and OpenET-Ensemble for the United States Continent [19; 20]. The lack of uniformity in the current model schemes made ET estimates more uncertain. LST-driven models do not have soil-water balancing and are preferred to use in crop ET monitoring due to their short temporal frequency and compatibility with crop phenology. Where ET in the semi-arid Mediterranean environment is very sensitive to soil moisture conditions, sub-surface hydrology in the soil plays a significant role in ET regulation [21; 22; 23; 24; 25]. ET methods need to increase their modeling precision in stress parameters and better space/time resolutions with good-quality data to improve the quality of predictions in water-stressed environments. Physically based soil-vegetation-atmosphere transfer (SVAT) models offer a more mechanistic representation of hydrological processes, coupling soil moisture dynamics, root zone interactions, and energy balance components. However, their application to diverse land use systems, such as rotational cropping, demands extensive parameterization and a large variable space [26]. Large-scale applications require multi-calibration techniques to enhance ET accuracy within a hydrological model because SVAT models often struggle to accurately capture ET in complex and heterogeneous landscapes [27]. The weak correlation between root zone soil moisture and canopy temperature under water-stressed conditions further emphasizes the challenges associated with these models [28]. Some SVAT modeling schemes use coupled Penman-Monteith and water balance approaches in a spatially explicit manner and simulate the coupled interactions between water and energy regimes. Such schemes connect deep soil hydrology with atmospheric fluxes realistically, they often require trial and error-based intensive parameterization with a comparatively large number of datasets [29; 30]. This study intends to explore which ET estimation approach is most suitable for the Mediterranean region in capturing spatial variability of ET across different ecosystems. With that aim, models based on energy balance, water balance, and coupled approaches are tested in which the first large-scale application of the SVAT model, STEPS, to the Mediterranean region is introduced with its comparison with other established models, i.e., SCOPE and TSEB. STEPS is a process-based model that dynamically calculates lateral water movement, runoff, soil moisture content, water table depth, and snowmelt, and integrates it all together and estimates ET on a daily scale. It adopts a \"four-leaf\" approach to stratify leaves based on moisture and sunlit conditions and solves water balance equations for each depth of the soil layer to represent diverse ecological and hydrological constraints in a spatially explicit manner [31]. Simulating the coupled behavior of water and energy cycle and accounting for subsurface lateral flux movement differentiates it from SCOPE and TSEB. In contrast, the SCOPE, being a radiative transfer model with energy balance calculations, first simulates spectral reflectance and transmittance of vegetation canopy and soil to derive fluxes of radiation, heat, water vapor, and carbon dioxide in the soil-atmosphere-vegetation continuum. It uses empirical and semi-empirical relationships and parameterizes the effects of soil moisture and LAI on canopy conductance and photosynthesis.