Wave attenuation in the Agulhas current

Abstract

The enlargement of surface wave height in the Agulhas Current, caused by waves propagating in the opposite direction to the current, is well known for its danger to large vessels traversing the Cape route. Occurrence characteristics of the phenomenon have recently been determined. This paper reports novel satellite observations of wave height reduction in the Agulhas Current, occurring when waves are more or less aligned with the flow. The reduction takes the form of a small but noticeable decrease in wave height; the maximum recorded reduction amounted to about one half of the undisturbed wave height. The phenomenon seems more prevalent in the northern parts of the Agulhas Current where the frequency of north-easterly swell is higher than in the south.