Chapter 07 - Ocean Circulation
The center of each of Earth's five major gyres coincides with the subtropics at about ____° north and south latitude. Because of this location these currents are called ______.
30°, Subtropical Gyres
Each subtropical gyre is composed of ___ main currents that flow progressively into one another.
4
All the layers of water affected by the Ekman Spiral combine to create a net movement of ____° from the direction of the wind. This average movement is called the ___________. The actual movement of the surface currents is less than ___° and Ekman Transport in the open ocean is ___° from the wind.
90°, Ekman Transport, 45°, 70°
Which deep water has the highest density?
Antarctic Bottom Water (AABW)
Which deep water has the lowest temperature?
Antarctic Bottom Water (AABW)
Which deep water has the lowest salinity?
Antarctic Intermediate Water (AAIW)
The two ocean currents that affect the coast of North America are the _______ (eastern boundary current) and _________ (western boundary current).
California Current, Gulf Stream
Ocean surface currents affect the _____ of the coastal regions of each continent. Poleward ocean currents along the western ocean basins transport ____ waters towards the pole and equator ward ocean currents along the eastern basins transport ____ waters toward the equator.
Climate, cold, warm
In reality, ocean surface currents are driven by more than just the wind belts of the world. The distribution of ______ on Earth influences the ____ and _____ of the flow of surface currents in each ocean basin. ______ and ______ create a circular current in the Atlantic Ocean basin, which is bounded by the irregular shape of the continents of ______, ______, and _____.
Continents, nature, direction, North and South America, Africa (?), Eurasia
In the Northern Hemisphere, the ______ causes surface water in contact with the wind to move in a direction 45° to the _____ of the wind direction. In the Southern Hemisphere, where Coriolis curvature is to the left, the surface layer moves 45° to the ______ of the wind direction.
Coriolis Effect, right, left
________ is the movement of warm, nutrient-depleted water from the ocean surface downward. It occurs in the open and coastal ocean where ______ causes surface water to converge or impinge on the coast. Downwelling is associated with ______ amounts of surface productivity but carries necessary dissolved _____ to organisms living on the deep-sea floor.
Downwelling, Ekman Transport, lower, oxygen
In addition to the wind belts there are other factor that influence subtropical gyre circulation patterns. List four additional factors.
Ekman Spiral, Ekaman Transport, Geostropic Currents, Western intensification of Subtropical Gyres
Coastal winds can cause upwelling or downwelling due to ________. Winds blowing from the north, parallel to the west coast of a continent in the Northern Hemisphere, cause the coastal waters to flow _____ from the shoreline. Deep-ocean waters _______ to replace water moving away from the shore in a process called _______.
Ekman Transport, away, rise up, coastal upwelling
The ______ describes the speed and direction of flow of surface waters at various depths. This model assumes that a uniform column of water is set in motion by ______ blowing across its surface. The direction surface water flows is a result of the balance between the ______ and the frictional effect on water molecules. Frictional effect reduces the water's _____ at depth.
Ekman spiral, wind, Coriolis Effect, speed
____________ is the movement of deeper nutrient-rich water onto the surface water as a result of _______ of surface currents along the equator. This current divergence creates areas of _____ productivity that are some of the most prolific ______ grounds in the world.
Equatorial Upwelling, diverging, high, fishing
Surface currents develop from ____ between the ocean and the wind that blows across its surface. Only about ___% of the wind's energy is transferred to the ocean surface, so a 50-knot wind will create a ___ -knot ocean current. Example: blow gently and steadily across a cup of coffee. Because wind belts drive the ocean's surface currents, and ____ is a result of uneven distribution of solar radiation, the ____ is the ultimate energy source for creating ocean surface currents.
Friction, 2, 1, wind, Sun
Which of the following currents contributes to the South Eastern United States being humid?
Gulf Stream
The ______ is a warm ocean current that affects England's climate. It carries warm water _____ from the _____ northward along the East Coast of the United States, warming coastal states and moderating winters in these states and norther European regions. The temperatures across the Atlantic, at different latitudes are much _____ in Europe than in North America.
Gulf Stream, poleward, equator, warmer
____ are huge circular-moving current systems that are driven by the major wind belts of the world and dominate the surface of the ocean within an ocean basin. Gyres help to balance the Earth's heat budget by redistributing ____ absorbed by the ocean from Solar Radiation in the lower latitudes, regions of _____ and transported to the higher latitudes, ______.
Gyres, heat, net heat gain, net heat loss
If there were no continents on Earth, the surface currents would follow the _____ of the world. In each hemisphere, a current would flow between 0° and 30° latitude as a result of the _____, a second would flow between 30° and 60° latitude as a result of the _______, and a third would flow between 60° and 90° latitude as a result of the _____.
Major wind belts, trade winds, prevailing westerlies, polar easterlies
Which deep water has the highest salinity?
Mediterranean Intermediate Water (MIW)
Which deep water has the lowest density?
North Atlantic Central Surface Water (NACSW)
The five subtropical gyres are:
North Pacific Subtropical Gyre, South Pacific Subtropical Gyre, North Atlantic Subtropical Gyre, South Atlantic Subtropical Gyre, and Indian Ocean Subtropical Gyre
Large currents move immense volumes of ocean surface waters throughout the various _____. Like major wind belts, surface currents transfer ____% of the total heat from the tropics to the poles and ocean surface currents transfer the remaining ___% of the total heat. Ocean surface currents are linked to the World's major wind belts proving both ocean currents and wind belts are driven by ____.
Ocean basins, 67, 33, Solar Energy
___ are masses of ocean water that flow from one place to another. The amount of water can be large or small, currents occur at the ocean's surface or at great depths in the ocean. Ocean currents are water ___ in mention and play an important role in influencing the various climates.
Ocean currents, masses
Western boundary currents are much warmer than eastern boundary currents because western boundary currents:
Originate from equatorial currents
Surface currents occur within and above the _____ to a depth of 1 km and affect about ___% of the world's ocean water. The worldwide pattern of ocean surface currents is influenced by the World's major _____, _____, _____, _____, and _____.
Pycnocline, 10, wind belts, gravity, the Coriolis effect, the distribution of continents, and the geometry of each ocean basin
In describing surface ocean currents, which of the following statements is not true of surface ocean currents?
Surface currents concentrate warm water in the center of the gyre at mid-latitudes giving the subtropics warm, moist air.
The ______ Diagram is used to identify deep-water masses based on their characteristic. With axes representing water temperature and salinity the _____ can be determined.
Temperature-Salinity (T-S), density
Because the density variations that cause deep ocean circulation are the result of differences in water temperature and salinity, deep-ocean circulation is called _____. This slow-moving current takes a year to travel the same distance that a western current can move in ___ hour.
Thermohaline Circulation, 1
Most water involved in deep-ocean currents ( ______ ) originates in high latitudes at the surface. In these regions, surface water becomes ____ and its salinity increases as sea ice forms. When this surface water becomes dense enough, it _____, initiating deep-ocean currents.
Thermohaline Circulation, cold, sinks
Two major wind belts that provide the energy to generate the subtropical gyres are:
Trade winds and Westerlies
________ is the upward vertical movement of cold, nutrient-rich, oxygen-rich water from beneath the pycnocline toward the ocean surface. This cold, nutrient-rich water creates an area of high ________ of marine life. Starting with an abundance of microscopic _____, the base of the food chain supports incredible numbers of larger marine life like ______ and ______.
Upwelling, productivity, algae, fish, whales
Density-driven circulation moves water ____ and accounts for the thorough mixing of the _____ masses of ocean water. Some surface waters become _____ in density, through low temperatures and/or high salinity and sink beneath the surface, so they are called _____.
Vertically, deep, high, deep currents
The observation that one subtropical boundary current is faster, narrower, and deeper than its counterparts is an example of which of the following?
Western Intensification
The apex of the hill of water formed within a rotating gyre is closer to the ______ than the geographic center of the gyre. As a result, the western boundary currents of the subtropical gyres are _____, ______, and _____ than their Eastern boundary current counterparts.
Western boundary, faster, narrower, deeper
Equatorial currents are ____ -flowing currents that travel along the ____, forming the _____ of subtropical gyres. These currents, the North or South Equatorial Currents depending on their position relative to the equator, are moved by the Northeast and Southeast ______.
Westward, equator, equatorial boundaries, trade winds
Ocean currents are either _______ or ________. ________ currents move water horizontally and occur in the ocean's surface waters, so they are called _______.
Wind-driven, density-driven, wind-driven, surface currents
Cold ocean currents ____ the nearby air, which is more likely to have _____ water vapor content.
cool, less
Increase in seawater density is a result of either a ______ in temperature or an ______ in salinity. _____ has a greater influence on density than salinity. Density changes due to salinity are important only at _____ latitudes where water temperature remains low and constant.
decrease, increase, Temperature, high
As ocean surface water masses become more _____, they sink as downwelling in high-latitude areas, concurrently, deep-water masses are also ______ to the ocean surface as upwelling.
dense, rising
Deep ocean currents are driven primarily by _____ and caused by _______ and _______.
density differences, differences in salinity, temperature
When the cool dry air travels over a continent the result is very little precipitation. Continental margins that have cool ocean currents offshore typically have ____ climates. The presence of a _____ current off the coast of California is part of the reason California climate is so _____.
dry, cold, arid
The pile of surface water within all subtropical gyres rises as much as 2 meters high. These hill of surface water in the subtropical connvergence tends to flow downhill in response to _____.
gravity
The Coriolis Effect opposes _____, deflecting the water to the right in a curved path back into the hill again. The net effect of the balancing of the two factors , gravity, and Coriolis Effect, results in the formation of the ______, which moves in a circular path around the hill within the gyre.
gravity, Geostrophic Current
Coastal upwelling along California is characterized by high concentration of nutrients, resulting in _____ productivity and rich ______ life. Coastal upwelling offshore of San Francisco creates low water temperature that results in much _____ weather and fog in the summer.
high, marine, cool
In the high-latitude regions, the ocean surface water is the same temperature as it is at depth, thus the water column is ______. The lack of a thermocline or associated ______ in the water column at the high-latitudes allows the upwelling and downwelling of ocean water to easily occur.
isothermal, pycnocline
The presence of a warm _____, off the East Coast of the United States helps explain why the area experiences such high humidity, especially during the _____ months.
ocean, summer
When warm moist air travels over a continent, it releases its water vapor in the form of ______. Continental margins that have warm currents offshore, typically have a _____ climate.
precipitation, climate
For coastal upwelling to occur, near shore water must be ________.
pushed seaward by wind or Ekman Transport
Ekman transport deflects surface water to the ____ in the Northern Hemisphere, so a _____ rotation develops within an ocean basin and produces the __________ of water in the middle of the gyre, causing water to pile up in the center of the ________.
right, clockwise, Subtropical Convergence, Subtropical Convergence
Coastal upwelling along the coast of Chile is a result of winds from the _____ turning towards the ______ due to Ekman Transport.
south, left
The _____ moves as a thin layer on top of deeper layers of the water column. As the wind blows across the ocean's surface, surface water begins to move. Wind _____ is transferred from the moving surface water to the layers beneath the surface. Each successive layer of water decreases in _______ and the _______ increases curvature to the right or left depending on the hemisphere.
surface water, energy, speed, Coriolis Effect
Winds blowing from the south, parallel to the west coast of a continent in the Northern Hemisphere, cause the waters offshore to flow ______ the shoreline. This stacks up the waters along the shoreline and with nowhere to go the water sinks in a process called _____________.
toward, coastal downwelling.
Current convergence occurs when surface waters move ______ each other causing the water to stack-up and no place to go but, slowly ____ in a process called _________. Areas of downwelling have _____ productivity because surface water is not being replenished with nutrients.
towards, sink, current convergence, low
Equatorial currents are driven by the ______.
trade winds
As dense water sinks, it is removed from the physical processes that increased its density, so its temperature and salinity remains _______ for the duration the water spends in the deep ocean.
unchanged
Diverging surface waters along the equator are areas of ______ and _______ productivity of marine life.
upwelling, high
Ocean surface currents influence the climate of the adjoining landmasses. Warm ocean currents _____ the nearby air. Warm air holds large amounts of water vapor, ______ the ________ of the atmosphere.
warm, increasing, moisture
This phenomenon of western currents is called _______________. An example of western intensification: the Kuroshio Current ( ________ ) is up to 15 times faster, 20 times narrower, and 5 times deeper than the California Current ( _________ ).
western intensification, Western Boundary Current, Eastern Boundary Current).
Prevailing westerlies push the northern and southern boundary currents ____ and eventually move into subpolar latitudes (60° N/S). At these latitudes the currents are turned and flow westward by the ______ creating ______ gyres that rotate opposite to the adjacent subtropical gyre.
westward, Polar easterlies, subpolar
Surface ocean currents are driven primarily by ______ and modified by ________ and ________.
wind, the Coriolis Effect, land
