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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, D15106, doi:10.1029/2006JD008362, 2007

Sunspots, El Niño, and the levels of Lake Victoria, East Africa

J. Curt Stager

Natural Sciences Division, Paul Smith's College, Paul Smiths, New York, USA
Climate Change Institute, University of Maine, Orono, Maine, USA


Alexander Ruzmaikin

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA


Declan Conway

School of Development Studies, University of East Anglia, Norwich, UK


Piet Verburg

Institute of Ecology, University of Georgia, Athens, Georgia, USA


Peter J. Mason

International Dams and Hydropower, High Wycombe, Bucks, UK


Abstract

An association of high sunspot numbers with rises in the level of Lake Victoria, East Africa, has been the focus of many investigations and vigorous debate during the last century. In this paper, we show that peaks in the ∼11-year sunspot cycle were accompanied by Victoria level maxima throughout the 20th century, due to the occurrence of positive rainfall anomalies ∼1 year before solar maxima. Similar patterns also occurred in at least five other East African lakes, which indicates that these sunspot-rainfall relationships were broadly regional in scale. Although irradiance fluctuations associated with the sunspot cycle are weak, their effects on tropical rainfall could be amplified through interactions with sea surface temperatures and atmospheric circulation systems, including ENSO. If this Sun-rainfall relationship persists in the future, then sunspot cycles can be used for long-term prediction of precipitation anomalies and associated outbreaks of insect-borne disease in much of East Africa. In that case, unusually wet rainy seasons and Rift Valley Fever epidemics should occur a year or so before the next solar maximum, which is expected to occur in 2011–2012 AD.

Received 15 December 2006; accepted 23 May 2007; published 7 August 2007.

Keywords: East Africa; ENSO; Lake Victoria; solar variability.

Index Terms: 4215 Oceanography: General: Climate and interannual variability (1616, 1635, 3305, 3309, 4513); 7536 Solar Physics, Astrophysics, and Astronomy: Solar activity cycle (2162); 4922 Paleoceanography: El Nino (4522); 4942 Paleoceanography: Limnology (0458, 1845, 4239); 9305 Geographic Location: Africa.

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Citation: Stager, J. C., A. Ruzmaikin, D. Conway, P. Verburg, and P. J. Mason (2007), Sunspots, El Niño, and the levels of Lake Victoria, East Africa, J. Geophys. Res., 112, D15106, doi:10.1029/2006JD008362.