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Is Solar Variability Reflected in the Nile River?We investigate the possibility that solar variability influences North African climate by using annual records of the water level of the Nile collected in 622-1470 A.D. The time series of these records are nonstationary, in that the amplitudes and frequencies of the quasi-periodic variations are time-dependent. We apply the Empirical Mode Decomposition technique especially designed to deal with such time series. We identify two characteristic timescales in the records that may be linked to solar variability: a period of about 88 years and one exceeding 200 years. We show that these timescales are present in the number of auroras reported per decade in the Northern Hemisphere at the same time. The 11-year cycle is seen in the Nile's high-water level variations, but it is damped in the low-water anomalies. We suggest a possible physical link between solar variability and the low-frequency variations of the Nile water level. This link involves the influence of solar variability on the atmospheric Northern Annual Mode and on its North Atlantic Ocean and Indian Ocean patterns that affect the rainfall over the sources of the Nile in eastern equatorial Africa.
Document ID
20070032665
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
Authors
Ruzmaikin, Alexander
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Feynman, Joan
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Yung, Yuk L.
(California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 23, 2013
Publication Date
November 11, 2006
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 111
ISSN: 0148-0227
Subject Category
Meteorology And Climatology
Funding Number(s)
CONTRACT_GRANT: NNG04GN02G
Distribution Limits
Public
Copyright
Other
Keywords
solar variability
climate variability

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