Composition and Chemistry
Isotopic composition of waters from Ethiopia and Kenya: Insights into moisture sources for eastern Africa
Article first published online: 8 DEC 2009
Copyright 2009 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 114, Issue D23, 16 December 2009
How to Cite
2009), Isotopic composition of waters from Ethiopia and Kenya: Insights into moisture sources for eastern Africa, J. Geophys. Res., 114, D23306, doi:10.1029/2009JD012166., , and (
- Issue published online: 8 DEC 2009
- Article first published online: 8 DEC 2009
- Manuscript Accepted: 3 SEP 2009
- Manuscript Revised: 26 JUN 2009
- Manuscript Received: 31 MAR 2009
- oxygen isotopes;
- eastern Africa
 Oxygen and deuterium isotopic values of meteoric waters from Ethiopia are unusually high when compared to waters from other high-elevation settings in Africa and worldwide. These high values are well documented; however, the climatic processes responsible for the isotopic anomalies in Ethiopian waters have not been thoroughly investigated. We use isotopic data from waters and remote data products to demonstrate how different moisture sources affect the distribution of stable isotopes in waters from eastern Africa. Oxygen and deuterium stable isotopic data from 349 surface and near-surface groundwaters indicate isotopic distinctions between waters in Ethiopia and Kenya and confirm the anomalous nature of Ethiopian waters. Remote data products from the Tropical Rainfall Measuring Mission (TRMM) and National Centers for Environmental Prediction (NCEP) reanalysis project show strong westerly and southwesterly components to low-level winds during precipitation events in western and central Ethiopia. This is in contrast to the easterly and southeasterly winds that bring rainfall to Kenya and southeastern Ethiopia. Large regions of high equivalent potential temperatures (θe) at low levels over the Sudd and the Congo Basin demonstrate the potential for these areas as sources of moisture and convective instability. The combination of wind direction data from Ethiopia and θe distribution in Africa indicates that transpired moisture from the Sudd and the Congo Basin is likely responsible for the high isotopic values of rainfall in Ethiopia.