Author(s)

Alain Tchakoutio^1,2,3*, Armand Nzeukou²

¹Department of Computer Science, Higher Technical Teachers Training College (HTTTC), University of Buea, Kumba, Cameroon.
²Laboratory for Environmental Modeling and Atmospheric Physics, Department of Physics, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon.
³Laboratory of Industrial Systems and Environmental Engineering, Fotso Victor Technology Institute, University of Dschang, Dschang, Cameroon.

The intraseasonal timescale is critical in Central Africa, because the resources of the region are highly rainfall dependent. In this paper, we use 1DD GPCP rainfall product to investigate the differences in the space-time structures of the 25 - 70-day intraseasonal variability of rainfall, over the Western Central Africa (WCA) and the Eastern Central Africa (ECA), with different climate features. The results of Empirical Orthogonal Functions (EOFs) analysis have shown that the amount of variance explained by the leading EOFs is greater in ECA (58.4%) than in WCA (49.8%). For both WCA and ECA, the power spectra of the Principal Components (PCs) peaked around 40 days, indicating a MJO signal. The seasonality of ISO is evident, but this seasonality is much noticeable in ECA where almost 80% of the total yearly ISO power occurs during November-April season, against only around 60% for WCA. Moreover, the lagged cross correlations computed between WCA and ECA PCs time series showed that most of the WCA PCs led ECA PCs time series with a timescale of 8 - 12 days, revealing that the eastward propagation could potentially be the relationship between WCA and ECA modes. The interannual variations in the ISO activity are weak in WCA, when compared with ECA where the signal exhibits larger interannual variations, quite linked with ENSO.

Rainfall, Intraseasonal Variability, Central Africa, EOF Analysis

Tchakoutio, A. and Nzeukou, A. (2016) On the Differences in the Intraseasonal Rainfall Variability between Western and Eastern Central Africa: Case of 25 - 70-Day Oscillations. Journal of Geoscience and Environment Protection, 4, 141-158. doi: 10.4236/gep.2016.47015.