OCE1001 Chapter 7

Surface ocean currents ______.

-Are influenced by Coriolis effect. -Form large rotating gyres in the major ocean basins. -Are driven by winds.

Which of the following methods are used to measure ocean surface currents directly?

-Radio-transmitting float bottles. -Accidental spills from container ships. -Free drifting Argo floats.

Which gyres move in a counterclockwise direction?

-South Pacific Subtropical Gyre -Indian Ocean Subtropical Gyre -Northern Hemisphere Subpolar Gyre -South Atlantic Subtropic Gyre.

Western intensification causes:

-Steeper slope of surface water in the section of the gyre as compared to the eastern section of the gyre. -Very swift western boundary currents. -A large volume of water within western boundary currents. -The center of the gyre to be shift to the west.

Ekman transport

-The Coriolis effect causes surface waters to move at an angle relative to the wind direction. -Ekman transport can result in upwelling or downwelling -Ekman transport is to the right in N. Hemisphere

Where would upwelling be expected to occur?

-Where seamounts or tablemounts are present. -Where there is a sharp bend in a coastline. -In areas of diverging surface currents.

In which direction does the surface current move in relation to the wind in the Southern Hemisphere?

45 degrees to the left.

To produce a surface current of 1.6 knots in the open ocean, a steady winds of ______ knots would be required.

80

Which of the following is the only current that completely circumscribes Earth?

Antarctic Circumpolar

Warm ocean currents ________.

Are warmer than the surrounding water.

Downwelling can result from ____________.

Converging surface current.

Which factors drive the Ekman transport?

Coriolis effect, Wind

Why do the lengths of arrows in the Ekman spiral get shorter and shallower as you move deeper into the water column?

Deeper water moves at a slower speed due to friction.

Converging surface waters are areas of ______ and _______ productivity.

Downwelling: Low

Equatorial currents that are part of the subtropical gyres flow ______. Equatorial countercurrents between gyres flow _______.

East to west, west to east.

The California Current is an example of which current?

Eastern Boundary Current

The Benguela current is an example of which current?

Eastern boundary Current.

Ocean frontal systems that spin off from currents such as the Gulf stream, akin to atmospheric storms, are known as _______.

Eddies.

Coastal winds can cause upwelling or downwelling due to ______.

Ekman transport.

The observation of ships and icebergs in the southern hemisphere float to the left of the wind direction due to _______.

Ekman transport.

Ocean surface currents

Form circular patterns in the major ocean basins called "gyres"

Which of the following two factors causes geostrophic circulation within a gyre?

Gravity and the Coriolis effect.

Which of the following currents contributes to the South Eastern US being humid?

Gulf Stream

Which ocean current is the strongest and faster in the world?

Gulf Stream.

Which of the following currents is responsible for Peru becoming the largest producer of fish, from the sea, in the world?

Humboldt Current

What is the Walker Circulation Cell?

It is the path that air takes as it moves from hight to low pressure, and back of high pressure, in the South Pacific under normal conditions.

Which surface currents transport large volumes of warm water to higher latitudes?

Kuroshio Current Gulf Stream Brazil Current

What is the effect of stronger winds under La Niña conditions?

Lowering the South Pacific ocean temperature from normal conditions.

Fluctuations in the flow of the Gulf Stream result in curving loops of water know as ________.

Meanders.

Gulf stream transports warm water into to _________.

North Atlantic.

Ocean surface currents transfer about _______ of the total amount of heat from the tropics to the poles.

One-third.

The subtropical gyres ______.

Play a large role in Climate.

Which of the following methods are used to measure ocean surface currents indirectly?

Pressure gradients.

Deep ocean currents ___________.

Result from changes in wind density.

If the ocean is warming faster in the Arctic polar regions than elsewhere .....

Slowing of deep ocean circulation, resulting in lower oxygen levels in deep water.

Between summer and winter, which of the following currents reveres its flow direction?

Somali Current

Which of the following Atlantic Subtropical gyre boundary currents is split into by a large landmass?

South Equatorial Current

Coastal upwelling along the coast of Chile is a result of winds from _______ turning towards the _________ due to Ekman transport.

South; Right

The observation of a hill of water within all subtropical gyres is an example of which of the following?

Subtropical convergence.

The El Niño Souther Oscillation can be best described as:

The relationship between sea surface temperature and changing atmospheric pressure.

What is Southern Oscillation?

The swapping of high and low pressure zones in the South Pacific under El niño conditions.

The Ekman spiral is causes by:

The wind and the Coriolis effect.

Deep ocean current movement is also known as ________.

Thermohaline flow.

About what percent of the wind's energy is transferred to the ocean surface?

Two

Under which conditions are droughts and wildfires common in Australia?

Under El niño conditions.

Surface waters are pushed away from land and are replaces by nutrient-rich bottom water through:

Upwelling

The Brazil current is an example of which of the following types of currents?

Western Boundary Current

The Kuroshio current is an example of which current?

Western boundary Current

Warm core rings are associated with

Western boundary currents

Why does upwelling occur along the west coast of S. America under normal conditions?

Winds moving westward in the South Pacific drive ocean currents toward the west; deep water rises to replace water driven westward.

The thermocline is _________.

a steep temperature gradient in the ocean that separates deeper cold water from warm upper water.

When a meander from the Gulf Stream pinches off into the warm water south of the current, the eddy is called a ________.

cold-core eddy or ring.

An increase in seawater density can be caused by a ________ in temperature or an _______ in salinity.

decrease, increase

Thermocline circulation is driven by

density differences

What forces drive water circulation in the deep ocean?

differences in water density, differences in water salinity, differences in water temperature.

Which direction do ocean currents in the S. Pacific move under El Niño conditions?

eastward.

During winter months, monsoon winds over the Indian Ocean:

flow from land to sea and are dry.

Cool ocean currents _________.

generally flow from high latitudes towards the equator.

Which process causes downwelling off the coast of Antartica?

ice formation.

In the southern hemisphere, the direction of the Ekman transport is always:

to the left of the wind direction

Equatorial currents are driven by the:

trade winds

Which is true about a western boundary current?

warmer water narrower current deeper current increased current velocity