Variation of Rainfall in Three Nigerian Stations, Using harmonic Analysis.

Abstract

This work is on the variation of rainfall using harmonic analysis for Portharcourt, Kano and Makurdi data, for the three stations the period of study covered 1977 to 2010, for which the time series plot, the amplitude, the first, second and third harmonics were generated. Portharcourt has a gently increasing trend with periodicities of 5 years for the first harmonic, 3.5 years for the second harmonic and seventeen years for the third harmonic respectively. Kano showed a declining trend, while the periodicities were 3 years for the first harmonic, 3 years for the second harmonic and 18 years for the third harmonic respectively. Makurdi’s semi-cyclical pattern has periodicities of 3 years for the first harmonic, 4 years for the second harmonic and 19 years for the third harmonic respectively.

Keywords: Rainfall; Variation; Harmonics; Periodicities.