Chapter 9 Flashcards
ocean circulation
what are ocean currents
mass flow of water (the term is usually reserved for
horizontal movement)
what are surface currents
the horizontal flow of water at or near the ocean’s surface
what is a thermohaline current
water circulation produced by differences in
temperature and/or salinity (and therefore density)
deep ocean circulation driven by differences in water density. which impacts around 90% of the ocean water.
Surface ocean circulation is driven primarily by _______ and modified by ________.
wind; the Coriolis effect and land
What is the primary driver of shallow oceanic circulation?
wind
what is a gyre
circuit of mid-latitude currents around the periphery of an ocean basin.
Most oceanographers recognize five gyres plus the Antarctic Circumpolar
Current
what is most commonly believed to be a potential impact of global warming on thermohaline circulation?
Melting ice caps near Greenland would input fresh water into the system, reducing the density of surface water and preventing it from sinking, thus slowing down the oceanic conveyor belt.
The large-scale circular patterns of ocean surface currents found in each ocean are known as
gyres
what are boundary currents
North-to-south or south-to north ocean surface current whose properties are influenced by the presence of a coastline.
what are western boundary currents
currents that run along the western side of the ocean basin (i.e. the east coasts of the continents). Since these currents come from the equator, they are warm water currents, bringing warm water to the higher latitudes and distributing heat throughout the ocean. It transports warm waters towards the poles in both hemispheres. It has an increased velocity.
It is a narrower current. It is a deeper current.
what are westerlies
the dominant wind bands between 30 and 60 degrees latitude in each hemisphere
what are eastern boundary currents
These currents come from high latitude areas, so they deliver cold water to the lower latitudes. Together, these currents combine to create large-scale circular patterns of surface circulation called gyres. In the Northern Hemisphere the gyres rotate to the right (clockwise), while in the Southern Hemisphere the gyres rotate to the left (counterclockwise).
what are the 5 major gyres
the North Atlantic, South Atlantic, North Pacific, South Pacific, and Indian
what is the north pacific gyre composed of
the North Equatorial Current on its southern boundary, which turns into the Kuroshio Current (a.k.a. the Japan Current) bringing warm water north towards Japan. The Kuroshio flows into the North Pacific Current which moves east towards North America, where it becomes the California Current to complete the gyre
what is the north Atlantic gyre composed of
North Equatorial Current flowing into the Gulf Stream along the east coast of the United States. The Gulf Stream merges into the North Atlantic Current to move water towards Europe, which then becomes the Canary Current as it moves south to join the North Equatorial Current.
what is the Antarctic Circumpolar Current (ACC)
the only current that connects all of the major ocean basins, and in terms of the amount of water that it transports, it is the largest surface current on Earth. creates the southern boundary for all of the Southern Hemisphere gyres. flows from west to east and is driven by westerlies
what is the south atlantic gyre composed of
the South Equatorial Current, the Brazil Current, the ACC, and the Benguela Current
what is the south pacific gyre composed of
the ACC becomes the Peru Current (also known as the Humboldt Current) moving up the west coast of South America, before joining the South Equatorial Current.
what is the indian gyre composed of
the ACC, the West Australia Current, the South Equatorial Current, and the Agulhas Current
what is a geostrophic gyre
A circular current around the periphery of an ocean basin in balance between the Coriolis effect and the pressure gradient
true or false: Thermohaline circulation generally creates faster currents than wind-driven surface circulation.
false
In the Pacific Ocean, the major currents flowing towards the equator are the:
California and Peru
true or false: In both hemispheres, western boundary currents transport warm water towards the poles
true
what is the gulf stream
the major surface current flowing northwards along the Atlantic coast of the U.S. and Canada
how is the gulf stream formed
from the convergence of the North Atlantic Equatorial Current bringing tropical water from the east, and the Florida Current that brings warm water from the Gulf of Mexico
what is western intensification
currents on the western side of a gyre are faster, deeper, and narrower than currents on the eastern side. The increase in speed of surface currents as they pass along the western boundary of an ocean basin. Due to coriolis effect
what is an eddy
Loop of swirling water, formed along the edge of a permanent current when two sides of a meander connect, trapping warm or cold water in its centre; it is still attached to the main current.
what are rings
Freestanding spinning mass of water that can be several hundreds of kilometres across and can exist for a few years; it can have a cold or warm centre.
what is a warm core ring
shallow, bowl-shaped water masses about 1 km deep, and about 100 km across, that rotate clockwise as they carry warm water in to the North Atlantic. Clockwise eddies
what are cold core rings
cone-shaped water masses extending down to over 3.5 km deep, and may be over 500 km wide at the surface. Counterclockwise eddies
what is ekman transport
Net water transport due to the Coriolis Effect in the upper 100 m of the ocean, which theoretical direction is 90° to the right of the wind direction in the Northern Hemisphere.
true or false: Ocean currents off of the east coast of a continent tend to be faster and stronger than those off of the west coast.
true
