Posted on 26 August 2020
SAWS is proud to announce the launch of a newly developed wave forecast system which incorporates the effects of regional ocean currents on waves. This is first for the region.
South Africa is home to one of the world's strongest ocean currents - the Agulhas Current. Strong currents have been shown to modulate ocean surface waves in their vicinity; for example, steepening waves where they oppose a current, or changing their direction of propagation when encountering one obliquely. This information is critical for safety of shipping. Global and regional operational wave forecasts available for the South African coastline do not take surface currents into account.
In order to advise users of potential surface current-induced changes to the wave climate along the South African east coast, a wave-current coupled forecast system has been designed and operationalised. The forecast system is a one-way coupled wave forecast in which forecast surface waves (from the SAWS SWaSS forecast system) interact with ocean surface currents from the Mercator global ocean forecast. The full details of this system can be found in the paper Toward Operational Wave-Current Interactions over the Agulhas Current by Barnes and Rautenbach (2020).
The forecast system is run once per day with a 72 hour lead-time and can be found under the Wave-current Interactions tab on the SAWS Marine Portal. Both coupled and uncoupled forecasts are presented together with the surface currents used to forced the coupled system.