Uncertainty in Satellite Remote Sensing Derived Evapotranspiration Estimation

Uncertainty in Satellite Remote Sensing Derived Evapotranspiration Estimation: Current Status and Assessment Methods

Tran, N.B. (TU Delft Water Resources; IHE Delft Institute for Water Education)
Van Der Kwast, Johannes (IHE Delft Institute for Water Education)
Mul, Marloes (IHE Delft Institute for Water Education)
Seyoum, S.D. (TU Delft Water Resources; IHE Delft Institute for Water Education)
Uijlenhoet, R. (TU Delft Water Resources)
Jewitt, G.P.W. (TU Delft Water Resources; IHE Delft Institute for Water Education)

Ortega-Sánchez, Miguel (editor)

2022

Evapotranspiration (ET), a key variable in both water and energy cycles. It is very challenging to measure or estimate in large regions. Among many approaches to estimate ET indirectly (e.g. through hydrological modelling), models that are based on satellite remote sensing data (RS) are increasingly being used. However, the RS-based models inherit uncertainty from many sources, such as the model’s algorithm and parameters, input satellite data, and processing techniques. It is challenging to assess this uncertainty due to limitations of validation data, high volume and high dimensionality of RS data. Many studies have evaluated uncertainty in RS-based estimation of ET using different methods and reference data. The suitability of methods and reference data subsequently affect the validity of these evaluations. Therefore, it is necessary to have an overview of different evaluation methods and their uses. This study aimed to systematically review original research papers that assessed uncertainty or accuracy of RS-ET model or data products. We categorized these papers and quantified based on (i) spatial and temporal scale of ET estimation, (ii) types of uncertainty, and (iii) methods used to assess uncertainty. Studies have been geographically concentrated in North Asia, North America, and Europe. Most studies used the validation method, which quantifies the discrepancy between pixel-based ET estimation with an in-situ estimation. Although a standardized validation approach for satellite-based ET estimates is not yet ready, most validation studies employed Eddy Covariance (EC) flux towers for reference estimation at field-scale. In regions where in-situ measurements are limited, many studies use the residual of the water balance as reference. However, few studies considered uncertainty in the reference estimation and mismatch of spatial and temporal scales. For monitoring agricultural fields, most RS-ET methods have been reported with high accuracy. When applying these methods to larger extent, additional assessments are required to better inform data users of the quality of RS-ET estimation. These include cross-validation, sensitivity, and uncertainty analyses. Overall, this review showed the progress in evapotranspiration estimation using satellite data in terms of uncertainty assessment.

Evapotranspiration
Remote sensing
Satellite data
Surface energy balance models
Uncertainty

http://resolver.tudelft.nl/uuid:2003d80c-4305-4f26-bc6c-d027533cbb1a

https://doi.org/10.3850/IAHR-39WC2521711920221782

IAHR

2023-12-24

978-90-832612-1-8

Proceedings of the 39th IAHR World Congress (Granada, 2022)

39th IAHR World Congress, 2022, 2022-06-19 → 2022-06-24, Granada, Spain

Proceedings of the IAHR World Congress, 2521-7119

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

conference paper

© 2022 N.B. Tran, Johannes Van Der Kwast, Marloes Mul, S.D. Seyoum, R. Uijlenhoet, G.P.W. Jewitt