In this paper, we analyze the space-time structures of the 10–25 day intraseasonal variability of rainfall over Central Africa (CA) using 1DD GPCP rainfall product for the period 1996–2009, with an emphasis on the comparison between 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 than WCA (40.6% and 48.1%, for WCA and ECA, resp.). For the two subregions, the power spectra of the principal components (PCs) peak around 15 days, indicating a biweekly signal. The lagged cross-correlations computed between WCA and ECA PCs time series showed that most of the WCA PCs lead ECA PCs time series with a time scale of 5–8 days. The variations of Intraseasonal Oscillations (ISO) activity are weak in WCA, when compared with ECA where the signal exhibits large annual and interannual variations. Globally, the correlation coefficients computed between ECA and WCA annual mean ISO power time series are weak, revealing that the processes driving the interannual modulation of ISO signal should be different in nature or magnitude in the two subregions. 1. Introduction The monitoring and prediction of climate in the tropics remain a crucial problem in the scientific community. It is well-known that many regions in the tropics are vulnerable to climate change because their resources are highly rainfall dependent. Amongst these regions, Central Africa (CA) is particularly vulnerable because the majority of its population is rural and practice rain-fed agriculture [1]. A strong rainfall intensity can result in devastating floods, whereas a weak rainfall is usually associated with droughts, thus affecting living conditions and the economy of the densely populated region in many sectors such as agriculture, livestock, and energy [2, 3]. The CA extends from 15°S to 15°N and 0–50°E mainly over the land and part of Atlantic and Indian Oceans on its edges (Figure 1). The topography of the region is quite various, including highlands, mountains, and Plateaus. The western part (15°S–15°N; 0–30°E) is consisting of the zones of intense precipitation, especially over the Congo Basin [4]. Some of the highest rainfall totals are reported over Mountain Cameroon, at its western edge, where mean annual rainfall exceeds 10 meters. The Congo basin was proven to experience one of the world’s most intense thunderstorms and highest frequency of lightning flashes [5, 6]. The western central Africa is
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