Oceanography Chapter 7 Ocean Circulation

Surface currents occur within and above the pycnocline to a depth of 1 kilometer and affect about ( ) of the world's ocean water.

10%

The pile of surface water within all subtropical gyres can ride up to ( ) meters high

2

What percent of the winds energy is transferred to the ocean's surface?

2%

How many subtropical gyres are there?

5

Wind belts transfer ( ) of the total heat from the tropics to the poles and ocean surface transfer the remaining ( ) of the total heat.

67% 33%

All the layers of water affected by the Ekman Spiral combine to create a net movement of ( )

90o from the direction of the wind This average movement is called the Ekman transport

What is artic convergence?

A zone of converging currents similar to the Antarctic Convergences but located in the arctic. An area of major sinking surface water

Equatorial and North/South currents transport what kind of water and to where

Across the equator

Which deep water has the highest density and lowest temperature? Which deep water has the lowest density and highest temperature? Which deep water has the highest salinity? Which deep water has the lowest salinity?

Antarctic Bottom Water North Atlantic Central Surface Water Mediterranean Intermediate Water Antarctic Intermediate Water

Why are they called the subtropical gyres?

Because they coincide with the subtropics at about 30o north and south latitude. (the location)

What does downwelling do?

Brings necessary dissolved oxygen to organisms living on the deep sea floor.

What are the two ocean currents that affect the coast of North America?

California Current (Eastern boundary current) and Gulf Stream Current (Western boundary current)

What kind of currents is the California and Gulfstream?

California Current is a Eastern current (cold) (dry climate) Gulfstream is a Western current (warm) (lot of rain)

This stacks up the waters along the shoreline and with nowhere to go, the water sinks in a process called?

Coastal downwelling

Deep ocean waters rise up to replace water moving away from the shore in a process called?

Coastal upwelling

Eastern currents transport what kind of water and to where

Cold (slow) to the equator

What does upwelling create?

Creates an area of high productivity of marine life. (Algae, fish, and whales)

Where do currents occur?

Currents occur at the ocean's surface or at great depths in the ocean.

Increase in seawater density is a result of either a .....

Decrease in temperature or an increase in salinity.

Why do these hills of surface water in the subtropical convergence tend to flow downhill?

Due to gravity

What other factors influence subtropical gyres?

Ekman Spiral, Ekman Transport, Western Intensification Subtropical Gyres, and Geostrophic Currents. (Major wind belts, continents, and Coriolis effect)

Coastal winds can cause upwelling or downwelling due to.....

Ekman Transport. Winds blowing from the North, parallel to the west coast of a continent in the Northern Hemisphere, cause coastal waters to flow away from the shoreline.

What do surface currents develop between the ocean and the wind that blows across its surface?

Friction

What are gyres?

Huge circular moving current systems that are driven by the major wind belts of the world. -Dominate the surface of the ocean within an ocean basin

Temperature has a greater.....

Influence on density than salinity. Density changes due to salinity only being important at high latitudes where water temperature remains low and constant.

As dense water sinks, it is removed from the physical processes that increased its density, so its temperature and salinity remain.....

Largely unchanged for the duration the water spends in the deep ocean.

Upwelling and downwelling occur in the .....

North Atlantic and near the continent of Antartica, creating deep water masses.

Where are they located?

North Pacific, North Atlantic, South Pacific, South Atlantic, and Indian Ocean.

( ) currents are masses of ocean water that flow from one place to another.

Ocean The amount of water can be large or small.

Ocean currents and wind belts are driven by?

Solar Energy

What is the ultimate energy for creating ocean surface currents?

Solar Radiation

Wind driven currents move water horizontally and occur in ocean's surface waters, they are called

Surface currents

What is an example of western intensification?

The Kuroshio Current (Western Boundary Current) which is up to 15 times faster, 20 times narrower, and 5 time deeper than the California Current (Eastern Boundary Current)

What do ocean surface currents affect in the coastal regions of each continent?

The climate

What is equatorial upwelling?

The movement of deeper nutrient rich water onto the surface water as a result of divergence of surface currents along the equator.

What is downwelling?

The movement of warm, nutrient depleted water from the ocean surface downward. Occurs in the open and coastal ocean where Ekman Transport causes surface water to converge or impinge on the coast.

Because the Coriolis effect opposes gravity, deflecting 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 Geostrophic Current, which moves in a circular path around the hill within the gyre.

What is the Ekman Spiral?

The speed and direction of flow of surface waters at various depths.

What is Ekman Transport?

The transfer of wind energy into the water.

What is upwelling?

The upward vertical movement of cold, nutrient rich, and oxygen rich water from beneath the pycnocline toward the ocean surface.

Winds blowing from the south, parallel to the west coast of a continent in the Northern Hemisphere, cause.....

The waters offshore to flow toward the shoreline.

Because of the apex hill of water formed within a rotating gyre is closer to the western boundary than the geographic center of the gyre.....

The western boundary currents of the subtropical gyres are faster, narrower, and deeper than their eastern boundary current counterparts.

Because the density variations that cause deep ocean circulation are the result of differences in water temperature and salinity, deep ocean circulation is called

Thermohaline Cirulation (This slow moving current takes a year to travel the same distance that a western current can move in 1 hour)

Where do equatorial currents flow?

They flow westward flowing and travel along the equator forming equatorial boundaries 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 Trade Winds.

What do gyres help with?

They help balance the Earth's heat budget by redistributing heat absorbed by the ocean from solar radiation in the lower latitudes, regions of Net Heat gain and transported to higher latitudes, Net Heat Loss.

As ocean surface water masses become more dense.....

They sink as downwelling in high-latitude areas, concurrently, deep water masses are also rising to the ocean surface as upwelling.

What does the Subtropical convergence of water in the middle of a gyre cause?

This causes water to pile up in the center of the subtropical gyre.

What does equatorial upwelling create?

This current divergence creates areas of high productivity that are some of the most prolific fishing grounds in the world.

Where do large currents move immense volumes of ocean surfaces waters?

Throughout the various ocean basins.

What do surface currents transfer?

Transfer heat from regions of net heat gain to regions of net heat loss.

What is the T-S Diagram?

Used to identify deep water masses based on their characteristic. (Temperature Salinity)

Density driven circulation moves water ( ) and ( )

Vertically and accounts for the thorough mixing of the deep masses of ocean water. -Some surface waters become high in density, through low temperatures and/or high salinity and sink beneath the surface, they are called deep currents

Western currents transport what kind of water and to where?

Warm (fast) to the poles

What is Equatorward?

Water is going from poles to equator.

What does poleward mean?

Water is going from the equator to the poles

What are the major wind belts that provide energy to generate the subtropical gyres?

Westerlies and the Trade Winds

What are the four currents part of the subtropical gyre?

Western North/South Eastern Equatorial

This phenomenon of western currents is called

Western Intensification

Ocean currents are driven by

Wind or density

What is thermohaline circulation?

deep-ocean currents are driven by differences in the water's density, which is controlled by temperature (thermo) and salinity (haline).

Ocean currents are water ( ) in motion and play an important role in influencing the various elements

masses

In south latitudes, the sources of deep water forms beneath the sea ice along Antarctica where.....

rapid freezing produces cold, high density water that sinks down the continental slope and spreads into all ocean basins and becomes Antarctic Bottom Water (densest)

Ekman transport deflects surface water to the ( )

right in the Northern Hemisphere, so a clockwise rotation develops within an ocean basic and produces the Subtropical Convergence of water in the middle of the gyre.

In the high latitude regions, the ocean surface water is the ......

same temperature as it is at depth, thus the water column is isothermal. The lack of thermocline or associated pycnocline in the water column at the high latitudes allows the upwelling and downwelling of ocean water to easily occur.

The world wide pattern of ocean surface currents is influenced by the world's major ....

wind belts, gravity, seasonal changes of the Coriolis effect, the distribution of continents, seasonal changes and the geometry of each ocean basin.