Cross-Shelf Exchanges in the South African EBC/WBC System

P. Ted Strub (Oregon State University, United States)


Ricardo P Matano (Oregon State University, United States)

Event: 2020 Ocean Surface Topography Science Team Meeting (virtual)

Session: Salient results from the 2017-2020 OSTST PIs

Presentation type: Type Forum

We report on our examinations of the interactions between the Agulhas Current, a Western Boundary Current (WBC) along the southeastern and southern coast of South Africa and the Benguela Current, an Eastern Boundary Current (EBC) along the southwestern coast of South Africa. This is the only pair of EBC and WBC systems that interact, due to the termination of the South African continent at a lower latitude than found in the other WBC/EBC systems. We are also conducting similar analyses of comparable WBC and EBC systems, namely the Brazil and Malvinas Currents (WBCs) along the eastern coast of South America and the Humboldt and California Currents (EBCs) along the western coasts of South and North America. Our analyses include:
• the evaluation of the previous (CNES-CLS13) and recent (CNES-CLS18) Mean Dynamic Topography fields and their associated long-term mean geostrophic surface velocities, after problems with the CLS13 fields were identified through interactions with South African colleagues and comparisons to new computer model fields;
• determination of the seasonal cycles of surface wind forcing from scatterometer data;
• development of a new high-resolution model of the circulation around the entire South African Continent;
• analysis of the alongtrack data available from the standard RADS data set and the coastally-focused ALES data set, in comparison to tide-gauge data along the SW African coast;
• further evaluation of the alongtrack data sets in comparisons to tide gauges along the US West Coast;
• determination of the long-term mean and seasonal circulations in the southern Benguela Current, the Agulhas Current, and over the Agulhas Bank inshore of the Agulhas Current, from both model and altimeter fields;
• descriptions of the Lagrangian trajectories that connect the Agulhas to the Benguela Current, both surface (altimeter and model) and subsurface (model);
• quantification of the water mass exchanges between the deep ocean and shelf, as well as the water mass transformations (model);
• and similar analyses in comparative WBC and EBC systems.
P. Ted Strub
Oregon State University
United States