A numerical investigation of the influence of monsoonal wind reversals over the East African coastal ocean

Includes abstract.Includes bibliographical references (leaves 81-94).In this dissertation, the variability in the East African coastal ocean (Somali basin) due to the monsoon transition is investigated. The monsoon is characterized by wind reversals and seasonality in the precipitation of a region. The surface circulation of the western Indian Ocean during the summer (JAS) and winter (JFM) monsoon winds is investigated using the Regional Ocean Modelling System (ROMS) ROMS is forced with the Comprehensive Ocean Atmosphere Data Sets (COADS) while the initial and lateral boundary conditions are derived from the World Ocean Atlas The domain area of the model study is constrained by 10•S to 15'N and 3S"E to 55"E, An overview of the surface circulation of the Somali basin is given. discussing the Somali Current East African Coastal Current, South Equatorial Counter Current Southern Gyre, and the Great Whirl The motivation of this dissertation is to improve the understanding of the circulation patterns within the Somali Basin from intra seasonal to seasonal timescales, using the ROMS model The model results suggest a seasonally reversing Somali current with a sub-surface counter current, consistent with observations_ Other prominent features such as the Great Whirl, which occurs during the Southwest monsoon and the Southern Gyre, are also apparent in the simulation The East African Coastal Current (EACC) and the South Equatorial Counter Current (SECCI are also major features of the Somali basin circulation that are equally apparent from the model simulation The model equally reproduces the equatorial jets as expected during the transition period of April/May and October/November with the net result of mass transport from the western end of the basin towards the east