Summary of Abstract Submission

Abstract Submission No. IO50-04-0019PresentationPoster

SURFACE CIRCULATION AND UPWELLING PATTERNS AROUND SRI LANKA AND FORMATION OF THE SRI LANKA DOME

Charitha Pattiaratchi*1, Saratha Wijeratne1, Danielle Su1

1 The University of Western Australia, Australia

ABSTRACT :

Sri Lanka occupies a unique location within the equatorial belt in the northern Indian Ocean and experiences bi-annually reversing monsoon winds. This allows for the island to interact with the reversing monsoon currents, leading to the island mass effect and enhanced primary production. This study explored elements of the dynamics of the surface circulation and coastal upwelling in the waters around Sri Lanka using satellite imagery and numerical simulations using the Regional Ocean Modelling System (ROMS). The results confirmed the presence of the reversing current system, between the equator and Sri Lanka, in response to the changing wind field: the eastward flowing Southwest Monsoon Current (SMC) during the Southwest (SW) monsoon transporting 11.5 Sv and the westward flowing Northeast Monsoon Current (NMC) transporting 9.5 Sv during the Northeast (NE) monsoon, respectively. A recirculation feature located to the east of Sri Lanka during the SW monsoon, the Sri Lanka Dome, is shown to result from the interaction between the SMC and the Island of Sri Lanka. Along the eastern and western coasts, during both monsoon periods, flow is southward converging along the south coast and the major upwelling region, during both monsoon periods, is located along the south coast. The location of the upwelling centre (flow convergence) was dependent on the relative strengths of wind driven flow along the east and west coasts: during the SW (NE) monsoon the flow along the western (eastern) coast was stronger migrating the upwelling centre to the east (west).