title: Intercomparison of Evapotranspiration Over the Savannah Volta Basin in West Africa Using Remote Sensing Data.
abstract: This paper compares evapotranspiration estimates from two complementary satellite sensors - NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and ESA's ENVISAT Advanced Along-Track Scanning Radiometer (AATSR) over the savannah area of the Volta basin in West Africa. This was achieved through solving for evapotranspiration on the basis of the regional energy balance equation, which was computationally-driven by the Surface Energy Balance Algorithm for Land algorithm (SEBAL). The results showed that both sensors are potentially good sources of evapotranspiration estimates over large heterogeneous landscapes. The MODIS sensor measured daily evapotranspiration reasonably well with a strong spatial correlation (R²=0.71) with Landsat ETM+ but underperformed with deviations up to ~2.0 mm day-1, when compared with local eddy correlation observations and the Penman-Monteith method mainly because of scale mismatch. The AATSR sensor produced much poorer correlations (R²=0.13) with Landsat ETM+ and conventional ET methods also because of differences in atmospheric correction and sensor calibration over land.
authors.affiliation: Department of Geography, Durham University, Science Site, Durham, DH1 3LE, UK. stephen.opoku-duah@durham.ac.uk.
authors.forename: S
authors.initials: S
authors.lastname: Opoku-Duah
authors.affiliation: Department of Geography, Durham University, Science Site, Durham, DH1 3LE, UK. danny.donoghue@durham.ac.uk.
authors.forename: D N M
authors.initials: DN
authors.lastname: Donoghue
authors.affiliation: Department of Geography, Durham University, Science Site, Durham, DH1 3LE, UK. t.p.burt@durham.ac.uk.
authors.forename: T P
authors.initials: TP
authors.lastname: Burt
keywords: AATSR; ET; MODIS; Remote Sensing; SEBAL; Volta basin; West Africa