Empirical Orthogonal Function (EOF) analysis is used to identify meteorological modes which contribute to East African rainfall variability and to delineate East Africa into rainfall homogeneous regions. The meteorological mode operating during the October-December season accounted for most of the variance ($\sim31$%). Four main rainfall homogeneous subregions were delineated. / Temporal and spatial variability of sea-surface temperatures (SSTs) are investigated using EOF analysis for the domain 40$\sp\circ$S to 25$\sp\circ$N and 50$\sp\circ$W to 80$\sp\circ$E. A large amount of variance is explained by the in-phase, El Nino/Southern Oscillation dominated signal first principal component: 28.6% for the Indian Ocean and 23.2% for the Atlantic Ocean. Homogeneous SST regions were delineated via rotation and areal-averaged time series for each homogeneous region were formed and analyzed. / In the Atlantic, an eastward propagation of SST anomalies was evident while within the Indian Ocean SST anomalies appeared to propagate westward. However, the Indian Ocean lags the Atlantic Ocean. There was a significant correlation ($\sim0.4$) between East African rainfall and SSTs over the tropical Indian Ocean. The correlation between the Atlantic SSTs and East African rainfall was less significant, but indicated that the eastern and tropical areas of the Atlantic had some influence on East African rainfall. / The regional SSTs series showed fluctuations being in-phase throughout the tropical and southeastern Atlantic Ocean and the west-central Indian Ocean. The SST fluctuations within these areas were almost in-phase and were also in-phase with East African rainfall. Their association is attributed to fluctuations of time scales of 2-2.5, 3-3.5 and 5-6 years. / The above normal rainfall in East Africa is associated with below normal southwest monsoon flow which is associated with less upwelling leading to above normal (warming) SSTs over North Indian Ocean and the Arabian Sea. Also, the tropical region east of 50$\sp\circ$E shows below normal westerly flow suggesting lower pressure near (or over) East Africa coast and filling of the semi-permanent trough south of India. However, the wind vector anomalies analysis is inconclusive because closer to the East African coast they do not support the observed wet or dry East African rainfall anomalies. / Source: Dissertation Abstracts International, Volume: 49-06, Section: B, page: 2232. / Major Professor: Sharon E. Nicholson. / Thesis (Ph.D.)--The Florida State University, 1988.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76322 |
| Contributors | Nyenzi, Buruhani Salum., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 208 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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