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24-826: The Canary Current is a wind-driven surface current that is part of the North Atlantic Gyre . This eastern boundary current branches south from the North Atlantic Current and flows southwest about as far as Senegal where it turns west and later joins the Atlantic North Equatorial Current . The current is named after the Canary Islands . The archipelago partially blocks the flow of the Canary Current (Gyory, 2007). This wide and slow moving current

48-678: A comparison to records of convective activity and water mass transformation at high latitudes in the North Atlantic. The OSNAP observing system, fully deployed in the summer of 2014, consists of moorings , gliders and RAFOS floats spanning the subpolar North Atlantic from Labrador to Greenland to Scotland. Measurement contributions come from the US, the UK, Germany, the Netherlands, Canada, China and France. Vigorous boundary currents crossing

72-769: Is a debate about the extent to which convection in the Labrador Sea plays a role in AMOC circulation, particularly in the connection between Labrador sea variability and AMOC variability. Observational studies have been inconclusive about whether this connection exists. New observations with the OSNAP array show little contribution from the Labrador Sea to overturning, and hydrographic observations from ships dating back to 1990 show similar results. Nevertheless, older estimates of LSW formation using different techniques suggest larger overturning. As with many oceanographic patterns,

96-716: Is theorised to hold true across the Atlantic in surface layers. The North Atlantic garbage patch is a garbage patch of man-made marine debris found floating within the North Atlantic Gyre, originally documented in 1972. A 22-year research study conducted by the Sea Education Association estimates the patch to be hundreds of kilometers across, with a density of more than 200,000 pieces of debris per square kilometer. The garbage originates from human-created waste traveling from rivers into

120-403: Is thought to have been exploited in the early Phoenician navigation and settlement along the coast of western Morocco . The ancient Phoenicians not only exploited numerous fisheries within this current zone, but also established a factory at Iles Purpuraires off present day Essaouira for extracting a Tyrian purple dye from a marine gastropod murex species. The current heavily influences

144-452: The meridional overturning circulation in the North Atlantic ( AMOC ) on interannual time scales. Though this linkage is evident in climate models on decadal time scales, to date there has been no clear demonstration of AMOC variability in response to changes in deep water formation on interannual and decadal time scales. OSNAP intends to fill that gap by providing a continuous record of the trans-basin fluxes of heat, mass and freshwater for

168-489: The seawater . Interannual trends have established that carbon dioxide concentrations within this gyre are increasing at a similar rate to that occurring in the atmosphere . This discovery concurs with that made in the North Pacific Gyre . The North Atlantic Gyre also undergoes temperature changes via atmospheric wave patterns. The North Atlantic Oscillation (NAO) is one such pattern. During its positive phase,

192-679: The East flank of Reykjanes Ridge, through the Charlie Gibbs Fracture Zone and then northward to join DSOW. These waters are sometimes referred to as Nordic Seas Overflow Water (NSOW). NSOW flows cyclonically following the surface route of the SPG (sub-polar gyre) around the Labrador Sea and further entrains Labrador Sea Water (LSW). Characteristically fresh Labrador Sea Water (LSW) is formed at intermediate depths by deep convection in

216-800: The Faroe-Shetland ridge flows through the Faroe-Bank Channel and soon joins that which flowed over the Iceland-Faroe ridge, to flow southward at depth along the Eastern flank of the Reykjanes Ridge. As ISOW overflows the GSR (Greenland-Scotland Ridge), it turbulently entrains intermediate density waters such as Sub-Polar Mode water and Labrador Sea Water. This grouping of water-masses then moves geostrophically southward along

240-549: The GSR (Greenland-Scotland Ridge) overflows. Most of the diverted LSW however splits off before the CGFZ (Charlie-Gibbs Fracture Zone) and remains in the western SPG. LSW production is highly dependent on sea-air heat flux and yearly production typically ranges from 3–9 Sv. ISOW is produced in proportion to the density gradient across the Iceland-Scotland Ridge and as such is sensitive to LSW production which affects

264-485: The North Atlantic Gyre experiences seasonal changes. Stramma and Siedler (1988) determined that the gyre expands and contracts with a seasonal variance; however, the magnitude of volume transport does not seem to change significantly. During the Northern Hemisphere winter season, the gyre follows a more zonal pattern; that is, it expands in the east-west direction and thins in the north-south direction. As

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288-585: The OSNAP line are directly measured in the Labrador and Irminger Seas by current meter arrays, and over the eastern flank of the Reykjanes Ridge by deep arrays. Geostrophic currents in the basin interior are estimated using temperature and salinity measurements from moorings and gliders. The AMOC is calculated on the basis of the directly measured boundary currents , the geostrophic currents and

312-635: The central Labrador Sea, particularly during winter storms. This convection is not deep enough to penetrate into the NSOW layer which forms the deep waters of the Labrador Sea. LSW joins NSOW to move southward out of the Labrador Sea: while NSOW easily passes under the NAC at the North-West Corner, some LSW is retained. This diversion and retention by the SPG explains its presence and entrainment near

336-440: The downstream density More indirectly, increased LSW production is associated with a strengthened SPG and hypothesized to be anti-correlated with ISOW This interplay confounds any simple extension of a reduction in individual overflow waters to a reduction in AMOC. LSW production is understood to have been minimal prior to the 8.2 ka event, with the SPG thought to have existed before in a weakened, non-convective state. There

360-414: The gyre warms. This is due to a weakening of the westerly winds , resulting in reduced wind stress and heat exchange , providing a greater period of time for the gyre water temperatures to rise. Measured samples of aerosols , marine particles, and water in the gyre from 1990–92 include examining lead isotope ratios. Certain isotopes are hallmarks of pollution essentially from Europe and

384-553: The near Middle East by trade winds ; other contamination was primarily caused by American emissions. The surface layers of the Sargasso Sea were read for such concentrations. 42–57% of the contamination came from American industrial and automotive sources, despite the reduction in the production and use of leaded gasoline in the United States. Since 1992 lead has clearly reducing concentrations – this

408-611: The ocean and mainly consists of microplastics . The garbage patch is a large risk to wildlife (and to humans) through plastic consumption and entanglement. Overturning in the Subpolar North Atlantic Program The Overturning in the Subpolar North Atlantic Program ( OSNAP ) is an international project designed to study the mechanistic link between water mass transformation at high latitudes and

432-502: The same way the North Pacific Gyre has the Great Pacific Garbage Patch . At the heart of the gyre is the Sargasso Sea , noted for its still waters and quite dense seaweed accumulations. Low air temperatures at high latitudes cause substantial sea-air heat flux, driving a density increase and convection in the water column. Open ocean convection occurs in deep plumes and is particularly strong in winter when

456-572: The sea-air temperature difference is largest. Of the 6 sverdrup (Sv) of dense water that flows southward over the GSR (Greenland-Scotland Ridge), 3 Sv does so via the Denmark Strait forming Denmark Strait Overflow Water (DSOW). 0.5-1 Sv flows over the Iceland-Faroe ridge and the remaining 2–2.5 Sv returns through the Faroe-Shetland Channel; these two flows form Iceland Scotland Overflow Water (ISOW). The majority of flow over

480-428: The seasons move from winter to summer, the gyre shifts south by a few degrees latitude. This occurs concurrently with the displacement of the northeastern part of the gyre. It has been concluded that zonal deviations within the gyre remain small while north and south of the gyre they are large. Data collected in the Sargasso Sea region in the western part of the North Atlantic Gyre has led to analytical evidence that

504-474: The variability of this gyre is linked to wintertime convective mixing . According to Bates (2001), a seasonal variation of 8-10 °C in surface temperature occurs alongside a fluctuation in the mixed layer depth between the Northern Hemisphere winter and summer seasons. The depth rises from 200 meters in winter to about 10 meters in summer. Nutrients remain below the euphotic zone for most of

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528-543: The weather of the Canaries and coastal Morocco , cooling down shoreline temperatures for much of the year and also causing vast deserts on coastlines due to the absence of convection above the cool water. Winds from the vast Saharan Desert to the east may still bring hot temperatures also to coastal areas. North Atlantic Gyre In turn it is chiefly subdivided into the Gulf Stream flowing northward along

552-684: The west; its often conflated continuation, the North Atlantic Current across the north; the Canary Current flowing southward along the east; and the Atlantic's North Equatorial Current in the south. The gyre has a pronounced thermohaline circulation , bringing salty water west from the Mediterranean Sea and then north to form the North Atlantic Deep Water . The gyre traps anthropogenic (human-made) marine debris in its natural garbage or flotsam patch , in

576-400: The year, resulting in low primary production . Yet during winter convective mixing, nutrients penetrate the euphotic zone, causing a short-lived phytoplankton bloom in the spring. This then lifts the mixed-layer depth to 10 meters. The changes in oceanic biology and vertical mixing between winter and summer in the North Atlantic Gyre seasonally alter the total amount of carbon dioxide in

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