Theoretical and Applied Climatology

, Volume 41, Issue 1–2, pp 41–53 | Cite as

Long-term variations of annual and growing season rainfalls in Nigeria

  • O. J. Olaniran
  • G. N. Sumner


Evidence for changes in the annual and growing season rainfall series for the period 1919 to 1985 in Nigeria are examined on a regional basis, using power-spectral and lowpass filter techniques, and the Mann-Kendall rank statistic. Four regions, the Coastal Zone, the Guinea-Savanna Zone, the Midland area and the Sahel, are used in the investigation of rainfall variation from south to north across the country.

Quasi-periodic oscillations in the annual and growing season rainfall series are found to be concentrated in four spectral bands: 2.0–2.4, 2.7–2.9, 3.2–3.6 and 5.6–6.3 years. The spatial coherence of the fluctuations in annual and growing season rainfall is found to be limited to Nigeria south of 11 degrees north latitude. Evidence also emerges of a progressive decline in annual and growing season rainfall for northern Nigeria, north of nine degrees north latitude, for the period 1939–1985.


Waste Water Coherence Nigeria Coastal Zone Lowpass Filter 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • O. J. Olaniran
    • 1
  • G. N. Sumner
    • 2
  1. 1.Department of GeographyUniversity of IlorinIlorinNigeria
  2. 2.Department of GeographySt. David's University CollegeLampeter, DyfedUK

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