Estimation of actual evapotranspiration using TDTM model and MODIS derived variables

Abstract

The objective of this paper is to contribute to improve ETa estimation in semiarid environments by proposing two variations to the TDMT model. These variations are based on the use of MODIS products from TERRA or AQUA satellites and on the use of NDVI instead of EVI, to estimate the fraction of vegetation cover. The proposed changes were validated with the original methodology for the 2012–2014 period with data obtained from two flux towers (ES-LJu and ES-Amo). The best results were obtained when using the alternative methodology (RMSE of 0.64–0.67 mm in ES-Lju and of 0.97–1.02 mm in ES-Amo). Additionally, a correction of the temporal systematic errors of the model based on RandomForest is proposed. With this correction, RMSE of 0.31–0.35 mm in ES-Lju and 0.30–0.34 mm in ES-Amo were obtained. The spatial distribution obtained with this corrected model is the most consistent with the characteristics of the study area.

Keywords:

• actual evapotranspiration
• MODIS
• TDTM
• flux towers
• random forest

Declaration of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, [F. G.-C.], upon reasonable request.

Additional information

Funding

This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness/Agencia Estatal de Investigación/FEDER [grant number CGL2017-84625-C2-2-R].