Ocean in Motion: Currents - Characteristics
Driven by forces such as wind, tides, and gravity, currents keep
our oceans in constant motion. Currents move large amounts of water
great distances. Countless currents have been named, but the seven
major ones are the West Wind Drift (or the Antarctic Circumpolar
Current), East Wind Drift, the North and South Equatorial currents,
the Peru Current, the Kuroshio Current and the Gulf Stream. These
currents flow in large rotating loops called gyres.
In the Northern Hemisphere, gyres spin in a clockwise direction,
and in the Southern Hemisphere, gyres spin in a counterclockwise
direction. This is because of Earth's spinning rotation and is called
the Coriolis Effect.
Large surface currents are mainly driven by winds that blow year
round. The winds at the equator are called the northeast
and southeast trade winds. At the mid-latitudes, the winds
are called the westerlies, and at the
highest latitudes, the winds are called the polar
easterlies. These winds blow in one direction all year.
Two of the largest currents are the Antarctic Circumpolar Current
and the Kuroshio Current. The Antarctic Circumpolar Current, sometimes
called the West Wind Drift, circles eastward around Antarctica.
The Kuroshio Current, which is located just off Japan's coast, travels
up to 75 miles a day at a speed of up to 3 miles per hour.
The Gulf Stream is a current with a strong influence on the East
Coast of the United States. Actually, the Gulf Stream is part of
a larger current system, which includes the North Atlantic Current,
the Canary Current and the North Equatorial Current. From the Yucatan
Peninsula in Mexico, the Gulf Stream flows north through the Straits
of Florida and along Florida's East Coast. When it reaches North
Carolina, around Cape Hatteras, it begins to drift off into the
North Atlantic towards the Grand Banks near Newfoundland. The Gulf
Stream usually travels at a speed of 3 or 4 knots.