Authors: K. Takahashi: Instituto Geofsico del Per , Lima, Per;
A. Montecinos: Departamento de Geofsica, Universidad de Concepcin, Concepcin, Chile;
K. Goubanova and B. Dewitte: Instituto Geofsico del Per , Lima, Per and Laboratoire d'Etudes en Gophysique et Ocanographie Spatiale, CNES/CNRS/IRD/UPS, Toulouse, France.
8. What triggers Canary Current's seasonal drift?
Along the northwestern coast of Africa lies an important fishery, stimulated by an upwelling of cold, nutrient-rich, deep-ocean water. Driven by a complex convergence of ocean currents, the waters between the coast, the Portuguese island of Madeira, and the Canary Islands are known to vary dramatically throughout the year, seeing coastal current reversals near the shore and the location of the large-scale Canary Current drifting seasonally, moving offshore in the winter before returning toward the coast in the summer. To sort out the trigger for this seasonal drift, Mason et al. produced a high-resolution model of the Canary Current that captures details of its interaction with the coastal region where the deep water upwelling occurs.
The authors find a pair of circular seasonal anomalies that they suggest control the strength and location of the Canary Current. The first, formed in late autumn, is a persistent, clockwise-spinning region of elevated sea surface height and increased flow rates. Its counterpart, a counterclockwise-rotating sea surface depression, is formed in the spring. Both anomalies spawn near the African coast and meander westward at around 2.6 kilometers per day (1.6 miles per day), pushing their way out of the region over the course of a year. The researchers report that the position of the Canary Current consistently lines up with the southward flowing edges of these anomalies and that this in turn explains the drift of the Canary Current. By selectively modifying parameters within their model, the aut
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American Geophysical Union