Comparison of Four Different Energy Balance Models for Estimating Evapotranspiration in the Midwestern United States

Ramesh Singh,Gabriel Senay

doi:10.3390/w8010009

Abstract

The development of different energy balance models has allowed users to choose a model based on its suitability in a region. We compared four commonly used models—Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC) model, Surface Energy Balance Algorithm for Land (SEBAL) model, Surface Energy Balance System (SEBS) model, and the Operational Simplified Surface Energy Balance (SSEBop) model—using Landsat images to estimate evapotranspiration (ET) in the Midwestern United States. Our models validation using three AmeriFlux cropland sites at Mead, Nebraska, showed that all four models captured the spatial and temporal variation of ET reasonably well with an R2 of more than 0.81. Both the METRIC and SSEBop models showed a low root mean square error (<0.93 mm·day−1) and a high Nash–Sutcliffe coefficient of efficiency (>0.80), whereas the SEBAL and SEBS models resulted in relatively higher bias for estimating daily ET. The empirical equation of daily average net radiation used in the SEBAL and SEBS models for upscaling instantaneous ET to daily ET resulted in underestimation of daily ET, particularly when the daily average net radiation was more than 100 W·m−2. Estimated daily ET for both cropland and grassland had some degree of linearity with METRIC, SEBAL, and SEBS, but linearity was stronger for evaporative fraction. Thus, these ET models have strengths and limitations for applications in water resource management.

Highlights

Modeling evapotranspiration (ET), the combined loss of water from soil through evaporation and from vegetation through transpiration, has many applications in agricultural management [1,2], carbon sequestration [3,4], climate modeling [5], drought monitoring [6], energy security [7], hydrological modeling [8], irrigation scheduling [9], and watershed development [10,11]
For both cropland and grassland had some degree of linearity with METRIC, Surface Energy Balance Algorithm for Land (SEBAL), and Surface Energy Balance System (SEBS), but linearity was stronger for evaporative fraction
We provide a brief overview of the models used in this study, and full details of the models are provided in their respective references

Summary

Introduction

Modeling evapotranspiration (ET), the combined loss of water from soil through evaporation and from vegetation through transpiration, has many applications in agricultural management [1,2], carbon sequestration [3,4], climate modeling [5], drought monitoring [6], energy security [7], hydrological modeling [8], irrigation scheduling [9], and watershed development [10,11]. Various models and techniques are used for accurately estimating ET at field to global scales. Many techniques such as lysimeters, sap flow, eddy covariance method, Bowen ratio system, and scintillometer are accurate and efficient but cannot be used for regional-to-global scale ET mapping due to prohibitive cost and logistical limitations. The availability of no-cost satellite images, advances in computing technology, and affordability of computing resources has allowed the development and use of remotely sensed images for water use estimation. Sensed images are increasingly used for estimating ET at different temporal and spatial scales. During the last two decades, many models were developed for estimating land surface

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