MAPPING ACTUAL EVAPOTRANSPIRATION AND SOIL MOISTURE IN TROPICAL WATERSHEDS

Tropical forests contain about half of the carbon present as biomass in the world's terrestrial ecosystems and turn out a mean annual evapotranspiration of about 1550 mm per year which exceeds that of any other land cover. Therefore, they play a major role in global carbon and water dynamics especially since carbon storage in tropical vegetation and evapotranspiration are so closely coupled. The objective of this contribution is to describe our research on the quantification and mapping of actual evapotranspiration in two tropical watersheds: the Rio Chagres basin in Panama and the White Volta Basin in Ghana. We will present maps of actual evapotranspiration and soil moisture prepared with the New Mexico Tech implementation of the Surface Energy Balance Algorithms for Land (SEBAL). These maps are derived from Landsat and MODIS images taken under clear sky conditions. We will also describe our approach to map actual evapotranspiration and soil moisture under cloudy conditions using GOES images and scintillometry.