Atlantic Ocean by three inter-connected currents: the Gulf Stream which flows north-east from the North American coast at Cape Hatteras; the North Atlantic Current, a branch of the Gulf Stream which flows northward from the Grand Banks; and 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
Atlantic Ocean variations, values may vary by . From October to June the surface is usually covered 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 during each 24 lunar hours. In latitudes above 40° North some east-west oscillation, known 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