## 3 Temperature-Based ET Models: Advantages, Drawbacks, and Evolution of Research
### Single-Source Surface Energy Balance Models
#### 3.1.1 The Surface Energy Balance System (SEBS)  
The Surface Energy Balance System (SEBS) was proposed for estimating atmospheric turbulent fluxes and evaporative fraction using satellite and meteorological data, and various parameterizations. It incorporates a new \(\mathrm{kB}^{-1}\) parameterization that considers canopy structure, adaptability to climate, and land cover variations [23]. In 2003, a modified version of SEBS incorporated radiometric data from the Along Track Scanning Radiometer (ATSR-2) to estimate atmospheric water vapor and aerosol optical depth. Sensible heat flux estimates from the modified SEBS were validated against measurements from large aperture scintillometers (LAS) in Spain [24]. SEBS was further evaluated using data from the Coordinated Enhanced Observing Period (CEOP), showing reasonable agreement at the tower scale but decreased accuracy with remotely sensed data and the Global Land Data Assimilation System (GLDAS) [25].  
In 2009, [PERSON] et al. 2009 evaluated SEBS for evapotranspiration estimation on a landscape scale, observing underestimation in dry, sparsely vegetated areas [26]. [PERSON] et al. 2013 identified biases in SEBS related to the parameterization of bare soil's resistance to heat transfer and proposed a revised parameter to improve performance [27].  
[PERSON] et al. 2019, calibrated key parameters in the SEBS model using thermal remote sensing data, resulting in improved accuracy for evapotranspiration calculations [28]. In 2021, [PERSON] et al. compared different approaches for accurate evapotranspiration estimation, with data-driven models outperforming SEBS [29]. Net radiation was crucial for all models, while temperature and humidity played a significant role in SEBS and a hybrid model.  
Furthermore, [PERSON] et al. (2023) addressed the underestimation of sensible heat flux in tall forest canopies by proposing a revised parameterization that considered the effect of turbulence on canopy heat transfer [30]. Evaluation using flux tower sites showed a significant reduction in underestimation, making the revised parameterization suitable for mapping surface heat fluxes in tall forest canopies.  
SEBS is often used for mapping surface turbulent heat fluxes due to its simplicity. Nevertheless, a common issue is the uncertainty in the parameter \(\mathrm{kB}^{-1}\) that accounts for differences in heat sources and momentum sinks in representing aerodynamic resistance. SEBS uses a constant value for the foliage heat transfer coefficient in its parameterization of \(\mathrm{kB}^{-1}\), which means that the impact of turbulence on canopy heat transfer is not considered. Consequently, the sensible heat flux in tall forest canopies where turbulence plays a crucial role in heat transfer is significantly underestimated. Hence, it is imperative to introduce a refined parametrization for \(\mathrm{kB}^{-1}\) to enhance the precision of sensible heat flux estimations, particularly in ecosystems characterized by tall forest canopies, where an accurate representation of turbulence-induced effects on heat exchange is crucial.