The Guajira upwelling system |
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| Institution: | 1. Departamento de Geociencias, Universidad Nacional de Colombia, Sede Bogotá, Colombia;2. Institut des Sciences de la Terre, Université Grenoble Alpes, CNRS, Grenoble, France;1. School of GeoSciences, University of Edinburgh, Edinburgh, UK;2. Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton, UK;3. British Antarctic Survey, Cambridge, UK;1. AZTI-Marine Research, Herrera Kaia, Portualdea z/g, 20110 Pasaia, Spain;2. Marine Technologies and Operational Oceanography Department, IMEDEA (CSIC-UIB), Esporles, Spain;3. SOCIB (Balearic Islands Coastal Observing System), Parc Bit, Edificio Naorte, 2nd floor, 07121 Palma de Mallorca, Spain;4. King Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Biological and Environmental Sciences and Engineering Division (BESE), Thuwal 23955-6900, Saudi Arabia |
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| Abstract: | The coastal upwelled waters of the Guajira coast, the most northerly peninsula of South America, were studied on the basis of historical data bases, remotely sensed data, and three oceanographic cruises. The Guajira Peninsula is the locus of particularly strong upwelling because it protrudes into the Caribbean Low-Level Wind Jet and its west coast parallels the direction of the strongest winds. The year-round upwelling varies with the wind forcing: strongest in December–March and July, and weakest in the October–November rainy season. The east–west temperature, salinity and density front that delimits the upwelling lies over the shelf edge in the east of the peninsula but separates from the south-westward trending topography to the west. A coastal westward surface jet geostrophically adjusted to the upwelling flows along the front, and an eastward sub-surface counterflow is trapped against the Guajira continental slope. The undercurrent shoals toward the western limit of the upwelling, Santa Marta, beyond which point it extends to the surface. Some of the westward jet re-circulates inshore with the counterflow but part continues directly west to form an upwelling filament. Much of the mesoscale variation is associated with upwelling filaments, which expel cooler, chlorophyll-rich coastal upwelling waters westward and northward into the Caribbean Sea. Freshwater plumes from the Magdalena and Orinoco rivers influence the area strongly, and outflow from Lake Maracaibo interacts directly with upwelled waters off Guajira. Another important factor is the Aeolian input of dust from the Guajira desert by episodes of offshore winds. |
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