Actual Evapotranspiration Estimation Using Remote Sensing: Comparison of SEBAL and SSEB Approaches

Bergson G Bezerra,José R C Bezerra,Bernardo B Da Silva,Carlos A C Dos Santos

doi:10.4236/ars.2015.43019

Abstract

The main objective of this paper was to evaluate the daily actual evapotranspiration (ET) accuracy obtained by remote sensing algorithms when compared with Bowen ratio measurements performed in the cotton fields. The experiment was conducted in a cotton experimental field of EMBRAPA located in Ceara State, Brazil. Seven TM Landsat-5 images acquired in 2005 and 2008 were used to perform SEBAL and SSEB algorithms. The comparison between the estimated values by remoting sensing algorithms and the measured values in situ showed an acceptable accuracy. Besides, SSEB algorithm showed to be an important tool for ET analysis in the semi-arid regions, due to the fact that it does not need the meteorological data to solve the energy balance, but only the average temperature of the “hot” and “cold” pixels. Additionally, SSEB presents simpler processing than SEBAL algorithm that needs to solve an iterative process to obtain the sensible heat flux values.

Highlights

Monitoring the spatial and temporal distribution of actual evapotranspiration (ET) is critically important for wa-How to cite this paper: Bezerra, B.G., da Silva, B.B., dos Santos, C.A.C. and Bezerra, J.R.C. (2015) Actual Evapotranspiration Estimation Using Remote Sensing: Comparison of SEBAL and SSEB Approaches
The primary methods used conventionally to measure ET are based on field scales (Bowen ratio, Eddy covariance method, soil water balance), but do not allow the estimation of fluxes when dealing with larger spatial scales because of the heterogeneity inherent in land surfaces and the dynamic nature of water vapor transport processes [6]
Note that the greatest uncertainty associated to SEBAL was verified in the estimates of H (MAPE > 60%) and G (MAPE∼40%)

Summary

Introduction

Monitoring the spatial and temporal distribution of actual evapotranspiration (ET) is critically important for wa-How to cite this paper: Bezerra, B.G., da Silva, B.B., dos Santos, C.A.C. and Bezerra, J.R.C. (2015) Actual Evapotranspiration Estimation Using Remote Sensing: Comparison of SEBAL and SSEB Approaches. The primary methods used conventionally to measure ET are based on field scales (Bowen ratio, Eddy covariance method, soil water balance), but do not allow the estimation of fluxes when dealing with larger spatial scales because of the heterogeneity inherent in land surfaces and the dynamic nature of water vapor transport processes [6]. They are unable to provide estimates of spatially distributed ET. [2] emphasizes that ET cannot be measured directly from satellites, but can be estimated based on surface radiation fields through semi-empirical remote sensing approaches such as SEBAL (Surface Energy Balance Algorithm for Land) [7] [8] and its variant METRIC (Mapping Evapotranspiration at High Resolution with Internalized Calibration) [9] [10], and M-SEBAL (Modified Surface Energy Balance Algorithm for Land) [11], beyond S-SEBI (Simplified Surface Energy Balance) [12]

Objectives

Results

Conclusion