Isotope Techniques For The Partitioning of Evapotranspiration Into Its Constituent Components

The hydrologic and biologic cycles of terrestrial ecosystem are liked through stomatal transpiration fluxes. Eddy covariance techniques are able to accurately measure ecosystem evapotranspiration (ET), yet the partitioning of this flux into its constituent components of evaporation (E) and transpiration (T) remains difficult. Various techniques utilizing stable isotopes have been developed for ET partitioning and this research area is advancing quickly. We present data collected from a newly-instrumented field site located in a semi-arid savanna ecosystem in central Kenya. The site is equipped with an eddy covariance system as well as a high frequency laser-based water vapor isotope analyzer. A suite of both isotope (Keeling plot, relaxed eddy sampling, etc.) and non-isotope ET partitioning methods are applied to a short term, high frequency data set from the 2010 field season and resulting E/T partitioning estimates are compared.