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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L10702, doi:10.1029/2004GL022156, 2005

Oscillatory modes of extended Nile River records (A.D. 622–1922)

D. Kondrashov

Department of Atmospheric and Oceanic Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA


Y. Feliks

Department of Atmospheric and Oceanic Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA


M. Ghil

Department of Atmospheric and Oceanic Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA


Abstract

The historical records of the low- and high-water levels of the Nile River are among the longest climatic records that have near-annual resolution. There are few gaps in the first part of the records (A.D. 622–1470) and larger gaps later (A.D. 1471–1922). We apply advanced spectral methods, Singular-Spectrum Analysis (SSA) and the Multi-Taper Method (MTM), to fill the gaps and to locate interannual and interdecadal periodicities. The gap filling uses a novel, iterative version of SSA. Our analysis reveals several statistically significant features of the records: a nonlinear, data-adaptive trend that includes a 256-year cycle, a quasi-quadriennial (4.2-year) and a quasi-biennial (2.2-year) mode, as well as additional periodicities of 64, 19, 12, and, most strikingly, 7 years. The quasi-quadriennial and quasi-biennial modes support the long-established connection between the Nile River discharge and the El-Niño/Southern Oscillation (ENSO) phenomenon in the Indo-Pacific Ocean. The longest periods might be of astronomical origin. The 7-year periodicity, possibly related to the biblical cycle of lean and fat years, seems to be due to North Atlantic influences.

Received 3 December 2004; accepted 8 April 2005; published 24 May 2005.

Index Terms: 1821 Hydrology: Floods; 3270 Mathematical Geophysics: Time series analysis (1872, 4277, 4475); 4215 Oceanography: General: Climate and interannual variability (1616, 1635, 3305, 3309, 4513).

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Citation: Kondrashov, D., Y. Feliks, and M. Ghil (2005), Oscillatory modes of extended Nile River records (A.D. 622–1922), Geophys. Res. Lett., 32, L10702, doi:10.1029/2004GL022156.