2024-03-28T08:26:26Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/269942020-11-12T09:08:51Zcom_10261_123com_10261_8col_10261_376
Mass fluxes in the Canary Basin
Machín, Félix
Hernández Guerra, Alonso
Pelegrí, Josep Lluís
Canary Basin
Water masses
Mass flux
Nutrient flux
Canary Current
Coastal upwelling
Inverse model
18-9W/27-33N
32 pages, 22 pages, 9 tables
Ocean studies in the 1970s provided an improved knowledge of the coastal upwelling region off NW Africa while in the 1980s and 1990s they led to a good description of the open ocean flow patterns in the Canary Basin. It was not until the late 1990s that major research addressed the open-coastal ocean coupled response. Here we examine the mean and seasonal circulation patterns in the Canary Basin with data from four hydrographic cruises carried out in the region between Cape Ghir, Madeira Island, and the Canary Islands. We apply an inverse box model to an ocean divided into 14 layers, with several layers representing each water mass or stratum, to obtain mass fluxes consistent with the thermal wind equation. An optimum flow description is obtained using conservation of mass, salt and heat anomaly, biologically corrected oxygen, and silicate, and allowing for Ekman transport in the surface layer and dianeutral mixing between adjacent layers. The deep waters show no predominant flow direction while the intermediate waters display localized southward flowing Mediterranean Water far from shore, and northward flowing Antarctic Intermediate Water near the continental slope, specially in the passage between the eastern Canary Islands and the African slope. The mean upper-thermocline Canary Current, composed of North Atlantic Central Water, flows south with an open-ocean branch transporting about 3 ± 1 Sv (1 Sv = 106 m3 s−1 congruent with 109 kg s−1), and an upwelling-related branch near the continental slope carrying 1 ± 0.3 Sv. The seasonal transport by the open-ocean branch intensifies and moves offshore from spring to fall (2.8 ± 1.2 Sv in spring, 2.9 ± 1.1 Sv in summer, and 4.5 ± 1.2 Sv in fall), while it carries its lowest southward mass flux in winter (1.7 ± 1.0 Sv), possibly as a result of a migration offshore the sampled region. Upwelling-related southward flow is present in spring and summer (1.9 ± 0.1 Sv and 2.4 ± 0.1 Sv, respectively) while in fall and winter it merges with the offshore southward branch. This westward migration allows a northward mass flux between the Canary Islands and the African coast (1.8 ± 0.1 Sv), that by winter reaches Cape Ghir (0.5 ± 0.2 Sv). Seasonal air–sea heat fluxes fit well with the climatological values. The net phosphate transport in the surface layer indicates that primary production was negligible in this region during January 1997 and April 1998, though in this last month production was probably starting as a result of significant nutrient supply
We acknowledge the support of the Spanish government through project CANOA (CTM2005-00444/MAR) and the European Union through projects CANIGO (MAS-CT96-0060) and OASIS (EVK3-CT-2002-00073). The first author thanks the Dirección General de Universidades e Investigación del Gobierno de Canarias for the grant received during his Ph.D
Peer reviewed
2010-08-12T07:18:00Z
2010-08-12T07:18:00Z
2006-08
artículo
http://purl.org/coar/resource_type/c_6501
Progress in Oceanography 70(2-4): 416-447 (2006)
0079-6611
http://hdl.handle.net/10261/26994
10.1016/j.pocean.2006.03.019
en
https://doi.org/10.1016/j.pocean.2006.03.019
none
5867 bytes
application/pdf
Elsevier