An Integrated Modeling Framework to Estimate Time Series of Evapotranspiration on a Regional Scale Using MODIS Data and a Two-Source Energy Balance Model

Abstract

Satellite remote sensing has become an important tool for monitoring and evaluating the impacts of drought. In this study, a modeling framework aimed at estimating the time series of evapotranspiration (ET), a key variable for drought monitoring, at a regional scale is presented. A two-source energy balance (TSEB) model was used concurrently with Terra/Aqua MODIS data and the ERA5 atmospheric reanalysis dataset. The modeling framework is based on the SEN-ET scheme to calculate the surface energy balance of the soil-canopy-atmosphere continuum and estimate ET at 1 km spatial resolution. The model was applied for the whole Iberian Peninsula, and it was evaluated with a pistachio orchard flux tower data in Lleida (NE Iberian Peninsula). Preliminary daily ET evaluation results for the Terra dataset showed an RMSE, MBE, and R2 of around 1.43 W·m−2, −1.27 W·m−2, and 0.56, respectively, and for the Aqua dataset were 1.05 W·m−2, −0.84 W·m−2 and 0.48, respectively within 100 days in 2022. Ongoing evaluation is being carried out on two forested watersheds as well as mountain meadows and semi-arid vegetation flux towers.

Keywords

• remote sensing
• drought
• evapotranspiration
• two-source energy balance
• water resource management
• MODIS