On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa
Volume 5, Issue 3, June 2016, Pages: 39-47
Received: May 25, 2016;
Accepted: Jul. 13, 2016;
Published: Jul. 23, 2016
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Alain Tchakoutio Sandjon, Department of Computer Science, Higher Technical Teachers Training College (HTTTC), University of Buea, Kumba, Cameroon; Laboratory of Industrial Systems and Environmental Engineering, Fotso Victor Technology Institute, University of Dschang, Bandjoun, Cameroon; Laboratory for Environmental Modeling and Atmospheric Physics, Department of Physics, Faculty of Sciences, University of Yaoundé 1, Yaoundé, Cameroon
Armand Nzeukou, Laboratory of Industrial Systems and Environmental Engineering, Fotso Victor Technology Institute, University of Dschang, Bandjoun, Cameroon
In this paper we analyzed the annual variations in the 25-70-day intraseasonal atmospheric oscillations in central Africa, for the period 1981-2010, using the Outgoing Longwave OLR data. We then extracted the amplitude time series of the dominant modes of intraseasonal variability in 25-70 days filtered OLR anomalies, using Empirical Orthogonal Functions (EOF) analysis. The EOF analysis has shown that three dominant modes characterized the intraseasonal atmospheric oscillation in Central Africa. The amount of variance explained by these three retained EOFs are 19.3%, 13.6% and 11.8% respectively, and they exhibit higher spatial loading over Northern Congo, Southern Ethiopia, and Southwestern Tanzania, respectively. The analysis of Principal Components (PCs) time series showed that the amplitude and of the intraseasonal oscillations (ISO) exhibit large annual variations. In fact the highest values of ISO amplitude are generally observed during October-April season, and much weakened signal the rest of the year. The fraction of yearly Madden Julian Oscillation (MJO) power, occurring within October-April season are 79.3%, 77.92%, 78.73% for EOF1, EOF2, and EOF3, respectively.
Alain Tchakoutio Sandjon,
On the Annual Variations in the Amplitude of 25-70-Day Intraseasonal Atmospheric Oscillations in Central Africa, Earth Sciences.
Vol. 5, No. 3,
2016, pp. 39-47.
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