The structure of incipient coastal counter currents in South Portugal as indicator of their forcing agents
Luciano De Oliveira Júnior, Erwan Garel, Paulo Relvas | This study investigates the physics that drive the development of westward, nearshore, currents along the south coast of Portugal (episodically bringing warm water in the region in summer and autumn). Based on a large current dataset, it is shown that these flows tend to develop near the bed first (and later near the surface), contrarily to the opposite, eastward, flows which are often observed near the surface first. This specific pattern of westward flows clearly indicates that they are generally not produced by local wind. Analytical considerations rather support that they result from the imbalance of an alongshore pressure gradient.
Keywords: Coastal flow; Upwelling circulation; Flow reversal; Alongshore pressure gradient; Gulf of Cadiz