Numerical modelling of the East African Coastal Current (EACC)

Majuto C. Manyilizu¹, Chris J. Reason¹, Alfonse M. Dubi<sup>2

1</sup>University of Cape Town, South Africa
²University of Dar es Salaam, Tanzania

Abstract
To date, there has been very little modelling of the East African coastal ocean in the Western Indian Ocean. This study applies the Regional Ocean Model System (ROMS) to this region (study domain of 5°N-15°S and 38°E-55°E) with a focus on the study of the monthly variability of the East African Coastal Current (EACC). The variability of the EACC during the monsoonal transitional seasons (April/May and October/November) is strongly focused. The ROMS was forced with the surface marine monthly climatology wind stresses and heat fluxes derived from individual observations in the Comprehensive Ocean-Atmosphere Data Set (COADS) from January, 1945 to December, 1989. The initial and lateral boundary conditions were derived from the World Ocean Atlas (WOA). The model output speeds of the EACC appear to be spatially and temporally varying throughout a year. The lowest spatial mean speeds of the EACC occurs during February (0.63ms^-1) whilst the maximum speeds is attained in July (1.13ms^-1) off the East African coast. Moreover, the monthly mean speeds of the EACC increase rapidly northward in April and through the austral winter. They subsequently decrease slowly through the rest of the year. Above all, during both monsoon transitional periods (April/May and October/November), the EACC attains speeds greater than 1ms^-1 north of 6°S.