Water characteristics
Surface water temperatures, which reconstruct with latitude, current systems, and season and reflect the latitudinal distribution of solar energy, range from below −2 °C 28 °F to over 30 °C 86 °F. Maximum temperatures arise north of the equator, and minimum values are found in the polar regions. In the middle latitudes, the area of maximum temperature variations, values may make adjustments to by 7–8 °C 13–14 °F.
From October to June the surface is normally pointed with sea ice in the Labrador Sea, Denmark Strait, and Baltic Sea.
The Coriolis effect circulates North Atlantic water in a clockwise direction, whereas South Atlantic water circulates counter-clockwise. The south tides in the Atlantic Ocean are semi-diurnal; that is, two high tides occur every 24 lunar hours. In latitudes above 40° North some east–west oscillation, call as the North Atlantic oscillation, occurs.
On average, the Atlantic is the saltiest major ocean; surface water salinity in the open ocean ranges from 33 to 37 parts per thousand 3.3–3.7% by mass and varies with latitude and season. Evaporation, precipitation, river inflow and sea ice melting influence surface salinity values. Although the lowest salinity values are just north of the equator because of heavy tropical rainfall, in general, the lowest values are in the high latitudes and along coasts where large rivers enter. Maximum salinity values occur at about 25° north and south, in subtropical regions with low rainfall and high evaporation.
The high surface salinity in the Atlantic, on which the Atlantic Agulhas Leakage/Rings, which brings salty Indian Ocean waters into the South Atlantic, and the "Atmospheric Bridge", which evaporates subtropical Atlantic waters and exports it to the Pacific.
The Atlantic Ocean consists of four major, upper water masses with distinct temperature and salinity. The Atlantic Subarctic Upper Water in the northernmost North Atlantic is the consultation for Subarctic Intermediate Water and North Atlantic Intermediate Water. North Atlantic Central Water can be dual-lane up into the Eastern and Western North Atlantic central Water since the western factor is strongly affected by the Gulf Stream and therefore the upper layer is closer to underlying fresher subpolar intermediate water. The eastern water is saltier because of its proximity to Mediterranean Water. North Atlantic Central Water flows into South Atlantic Central Water at 15°N.
There are five intermediate waters: four low-salinity waters formed at subpolar latitudes and one high-salinity formed through evaporation. Arctic Intermediate Water, flows from north to become the point of reference for North Atlantic Deep Water south of the Greenland-Scotland sill. These two intermediate waters produce different salinity in the western and eastern basins. The wide range of salinities in the North Atlantic is caused by the asymmetry of the northern subtropical gyre and the large number of contributions from a wide range of sources: Labrador Sea, Norwegian-Greenland Sea, Mediterranean, and South Atlantic Intermediate Water.
The Antarctic Bottom Water and Mediterranean Overflow Water.
The NADW is fed by a flow of warm shallow water into the northern North Atlantic which is responsible for the anomalous warm climate in Europe. Changes in the profile of NADW cause been linked to global climate changes in the past. Since man-made substances were offered into the environment, the path of the NADW can be traced throughout its course by measuring tritium and radiocarbon from nuclear weapon tests in the 1960s and CFCs.
The clockwise warm-water North Atlantic Gyre occupies the northern Atlantic, and the counter-clockwise warm-water South Atlantic Gyre appears in the southern Atlantic.
In the North Atlantic, surface circulation is dominated by three inter-connected currents: the Subpolar Front, an extension of the North Atlantic Current, a wide, vaguely defined region separating the subtropical gyre from the subpolar gyre. This system of currents transport warm water into the North Atlantic, without which temperatures in the North Atlantic and Europe would plunge dramatically.
North of the North Atlantic Gyre, the cyclonic North Atlantic Subpolar Gyre plays a key role in climate variability. it is governed by ocean currents from marginal seas and regional topography, rather than being steered by wind, both in the deep ocean and at sea level.
The subpolar gyre forms an important part of the global Sv current which flows around the continental margins of the Labrador Sea. A third of this water becomes part of the deep portion of the North Atlantic Deep Water NADW. The NADW, in its turn, feeds the meridional overturning circulation MOC, the northward heat transport of which is threatened by anthropogenic climate change. Large variations in the subpolar gyre on a decade-century scale, associated with the North Atlantic oscillation, are particularly pronounced in Labrador Sea Water, the upper layers of the MOC.
The South Atlantic is dominated by the anti-cyclonic southern subtropical gyre. The South Atlantic Central Water originates in this gyre, while Angola Gyre lies embedded in the large subtropical gyre.
The southern subtropical gyre is partly masked by a wind-induced North Atlantic Deep Water flows southward below the thermocline of the subtropical gyre.
The Sargasso Sea in the western North Atlantic can be defined as the area where two line of Gulf Stream, North Atlantic Drift, and North Equatorial Current. This population of seaweed probably originated from Tertiary ancestors on the European shores of the former Tethys Ocean and has, whether so, remains itself by vegetative growth, floating in the ocean for millions of years.
Other quality endemic to the Sargasso Sea add the Carpathian Basin from where it migrated over Sicily to the Central Atlantic where it evolved into advanced species of the Sargasso Sea.
The location of the spawning ground for European eels remained unknown for decades. In the early 19th century it was discovered that the southern Sargasso Sea is the spawning ground for both the Earth's magnetic field to navigate through the ocean both as larvae and as adults.