Abstract
East Africa is characterized by a rather dry annual precipitation climatology with two distinct rainy seasons. In order to investigate sea surface temperature driven precipitation anomalies for the region we use the algorithm of empirical orthogonal teleconnection analysis as a data mining tool. We investigate the entire East African domain as well as 5 smaller sub-regions mainly located in areas of mountainous terrain. In searching for influential sea surface temperature patterns we do not focus any particular season or oceanic region. Furthermore, we investigate different time lags from zero to twelve months. The strongest influence is identified for the immediate (i.e. non-lagged) influences of the Indian Ocean in close vicinity to the East African coast. None of the most important modes are located in the tropical Pacific Ocean, though the region is sometimes coupled with the Indian Ocean basin. Furthermore, we identify a region in the southern Indian Ocean around the Kerguelen Plateau which has not yet been reported in the literature with regard to precipitation modulation in East Africa. Finally, it is observed that not all regions in East Africa are equally influenced by the identified patterns.
Highlights
In contrast to other tropical areas, East Africa is characterized by a rather dry annual precipitation climatology
CHIRPS is a 30+ year quasi global rainfall data set, which is available from 1981 until the recent present and has a resolution of 0.05 ◦ × 0.05 ◦. It incorporates a number of satellite precipitation products including Tropical Rainfall Measuring Mission (TRMM), rainfall fields from NOAA’s Climate Forecast System version 2 (CFSv2) as well as in situ precipitation observations
We focus on the description of the results found for the entire East African domain and provide references to the corresponding findings within the sub-domains where approproate
Summary
In contrast to other tropical areas, East Africa is characterized by a rather dry annual precipitation climatology. The major rainy season, the so-called “long rains” is from March until May (MAM), while the second rainy season from October to December (OND), the “short rains” is more variable but usually centered around November The modulation of these rainy seasons by regional to global sea surface temperature (SST) anomalies has been the focus of numerous studies in the past (e.g., Rocha and Simmonds, 1997; Mutai et al, 1998; Latif et al, 1999; Plisnier et al, 2000; Behera et al, 2005; Black, 2005; Marchant et al, 2007; Ummenhofer et al, 2009; Manatsa et al, 2012, 2014; Manatsa and Behera, 2013; Bahaga et al, 2015; Tierney et al, 2015). There is, a clear tendency of most of these studies to (i) focus on particular seasons and/or (ii) focus on the influences of one or two predefined (coupled) ocean (-atmosphere) indeces such as IOD or ENSO
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