chapter 9

Water adjacent to a western boundary current is often ___ and ___

Cold / Capable of hosting life

16. How might weather in the western United States be affected by El Niño?

Greater evaporation of water from the warm ocean surface, combined with an increased number of winter storms steered into the western United States by the southward-trending jet stream, can double rainfall amounts and increase coastal erosion.

Why are Washington DC summers so hot?

Heat and moisture from the Gulf stream contribute the capitals oppressive Summers

9. How does wind blowing over a surface current influence the climate downwind?

If a continent is downwind of a mass of warm water, the atmosphere will transfer some of the heat to the continent. For example, the mild climates of Edinburgh, Dublin, and London are due to eastward-moving air only recently in contact with the relatively warm North Atlantic Current.

How is downwelling different from upwelling

Downwelling has no direct effect on the climate or productivity of the adjacent coast

What does downwelling do

Downwelling help supply the deeper ocean with dissolved gases and nutrients and it assist in the distribution of living organisms

Why don't water masses mix

Due to their different densities instead they usually flow above or beneath each other

Warm

core eddies rotate ___ and cold-core eddies rotate ___. - Clockwise, Counterclockwise

When does coastal upwelling occur

Coastal upwelling occurs when water rising along the shore replaces the surface water

Eastern boundary currents carry ___ water equatorial. They are ___.

Cold / Shallow

3. What is a gyre? How many large gyres exist in the world ocean? Where are they located?

A gyre is a circuit of wind-driven current flow around the periphery of an ocean basin. There are six major gyres in the world ocean: North and South Pacific, North and South Atlantic, Indian Ocean, and the West-Wind Drift (Antarctic Circumpolar Current).

23. Using common objects, could you conduct research on ocean currents?

Because they're biodegradable and float with nearly even with the water surface (and are therefore not unduly influenced by winds), citrus fruits make great current trackers is enclosed harbors and bays. Farther afield, the dependable message-in-a-bottle works well. Just be sure to provide any reward you promise to the sender!

What determines the characteristics of each mass

Conditions of heating cooling evaporation and the dilution that occurred at the ocean surface when the mass formed

What drives a slow circulation of water great depths?

Density differences

Why might it be a little warmer in the winter in Europe?

Europe is warmed and part by the energy up tropical sun my transported to high latitudes by the golf stream

How was the hill in the Sargasso Sea formed?

It was formed of surface water gathered at the oceans center of circulation.

15. How is La Niña different from El Niño?

La Niña is the usual configuration of equatorial winds in the Pacific basin. -- Afteran ENSO event normal circulation sometimes returns with surprising vigor,producing strong currents, powerful upwelling, and chilly and stormy conditionsalong the South American coast. These contrasting colder-than-normal events aregiven a contrasting name: La Niña

What causes circulation patterns near the surface of the water and why?

Local and global wind patterns, the earths rotation, and continental blockage.

Westerlies travel from the __ to the __ and trade winds (easterlys) travel from the __ to the __

Southwest, northeast. Northeast, southwest.

1. What causes the two major types of ocean currents?

Surface currents are wind-driven movements of water at or near the ocean's surface, and thermohaline currents are the slow deep density-driven currents that affect the vast bulk of seawater beneath the pycnocline.

Name the five common water masses a temperate and tropical latitudes?

Surface water, central water , intermediate water, deep water, bottom water

How does the Coriolis effect intervene with traveling surface currents?

The Coriolis effect causes the surface currents in the northern hemisphere to flow to the right of wind direction and in the southern hemisphere to the left of the wind direction.

What propels gyres and holds them along the outside of ocean basins?

The balance of wind energy, friction, the Coriolis effect and the pressure gradient.

20. Where are distinct water masses formed?

The characteristics of each water mass are usually determined by the conditions of heating, cooling, evaporation, and dilution that occurred at the ocean surface when the mass was formed.

22. Compare the length of time required for completion of a circuit of surface circulation to that needed for thermohaline circulation.

The circulation time of most deep water about 200 to 300 years. In contrast, a bit of surface water in the North Atlantic gyre may take only a little more than a year to complete a circuit.

12. Which way does wind typically blow over the tropical Pacific? How does this flow change during an El Niño event?

The trade winds blow from the normally high-pressure area over the eastern Pacific (near Central and South America) to the normally stable low-pressure area over the western Pacific (north of Australia). However, for reasons that are still unclear, these pressure areas change places at irregular intervals.

Why is upwelling important process

The water from with in and below the pycnoline is often rich in the nutrients that marine organisms need for growth

11. How is the Coriolis effect involved in equatorial upwelling?

Though the Coriolis effect is weak near the equator (and absent at the equator), water moving in the currents on either side of the equator is deflected slightly poleward and replaced by deeper water (Figure 8.14). Thus, equatorial upwelling occurs in these westward-flowing equatorial surface currents.

21. How does thermohaline circulation force the thermocline toward the ocean's surface?

Water sinks relatively rapidly in a small area where the ocean is very cold, but it rises much more gradually across a very large area in the warmer temperate and tropical zones. The continual diffuse upwelling of deep water maintains the existence of the permanent thermocline found everywhere at low and mid-latitudes.

How do winds drive surface currents?

Waves on the sea surface transfer some of the energy from the moving air to the water by friction, beginning a mass flow of water. The water flowing beneath the wind forms a surface current.

Upwelling is linked to the biological productivity how?

When that water rises toward the sunlit surface, biological productivity increases (from pycnocline)

2. About what percentage of the world ocean is involved in wind

driven surface currents? - About 10% of the water in the world ocean is involved in surface currents driven by wind friction.

25. How can chlorofluorocarbons (CFCs) be used as such tracers? Would CFC based methods be equally suitable for analysis of surface currents and thermohaline circulation?

- Because they dissolve easily in seawater, chlorofluorocarbons (CFCs) can be used as current tracers. A totally artificial chemical first produced in the 1930s for use as refrigerants, aerosol propellants, and blowing agents for foam, CFCs spread through the ocean like a dye, following oceanic circulation. The speed of thermohaline currents has been measured by careful analysis of their CFC content.

24. Traditional methods of studying currents are being replaced with high tech devices. How do some of these work?

- Modern research on currents is being carried out by devices that measure current speed by sensing the electromagnetic force generated by seawater as it moves in Earth's magnetic field, Doppler current profilers that project beams of sonic pulses ("pings") into the water each second, autonomous gliders like the Slocums, and other promising technologies.

10. How can wind driven horizontal movement of water induce vertical movement in surface water?

- The friction of wind blowing from the north along the ocean surface causes the water next to the west coast of a continent to begin moving. Coriolis effect deflects the water to the right (in the Northern Hemisphere), and the resultant Ekman transport moves it offshore. Deep water then rises (moves vertically) to replace the seaward-moving surface water.

Where is density stratification most pronounced

A temperate and tropical latitudes because the temperature difference between surface water and Deepwater is greater there than near the poles

19. What are water masses? What determines their relative position in the ocean?

A water mass has distinct temperature and salinity characteristics. The relative positions of water masses depend on their densities. Water masses don't often mix easily when they meet due to their differing densities; instead, they usually flow above or beneath each other.

How can surface currents affect places like California?

Air normally flows clockwise and some around an offshore zone of high atmospheric pressure when approaching the California coast loses heat to the cold sea and comes ashore chill

How are the densest masses formed?

By surface conditions that created very cold and salty water conditions

How does the Coriolis effect effect gyres?

Eastward moving water on the north side of the north atlantic gyre turns sooner and more strongly toward the equator than westward flowing water at the equator turns toward the poles.

13. What is the Southern Oscillation? How is this related to El Niño?

In the Southern Oscillation, winds across the tropical Pacific reverse direction and blow from west to east—the trade winds weaken or reverse.

What happens to the water the next layer down during a flow around the ocean basins?

It cant feel the wind at the surface. It can feel only the movement of water immediately above. This deeper layer of water moves at an angle to the right of the overlying water.

Why is Ekman transport in gyres barely reach forty five degrees?

It's due to the Coriolis effect and pressure gradient.

7. What is meant by "westward intensification?" Why are western boundary currents so fast and deep?

Let's use a Northern Hemisphere example. Due to the Coriolis effect—which increases as water moves farther from the equator—eastward-moving water on the north side of a gyre is turned sooner and more strongly toward the equator than westward-flowing water at the equator is turned toward the pole. So the peak of the hill described in Figure 8.7 is not in the center of the ocean basin, but closer to its western edge. Its slope is steeper on the western side. If an equal volume of water flows around the gyre, this means the current on the eastern boundary is spread out and slow, and the current on the western boundary is concentrated and rapid.

What are conditions like at the center of a gyre?

Low energy with waters obtaining high amounts of salt and light winds.

Western boundary currents ___ as they flow.

Meander

What happens after a surface current is formed?

Moving water 'piles up' in the direction the wind is blowing. Water pressure is higher on the 'piled up' side and the force of gravity pulls water down the slope against the pressure gradient.

One sverdeup equals how many cubic meters per second?

One million.

Water in gyres is balanced between __ and __

The downhill urge of the pressure gradient, the uphill tendency of Coriolis deflection.

How does wind induce upwelling?

The friction of wind blowing along the ocean surface causes the water to begin moving the Coriolis effect the flex it to the right and the resultant Ekman transport moves it offshore

17. What drives the vertical movement of ocean water?

The slow circulation of water at great depths is driven by density differences rather than by wind energy. The whole ocean is involved in slow thermohaline circulation, a process responsible for the large-scale vertical movement of ocean water and the circulation of the global ocean as a whole.

Through the Coriolis effect what happens to water moving in the currents on either side of the equator?

The water is deflected slightly poleward and is replaced by deeper water

Why does water flow around the periphery of the ocean basin instead of spiraling to the center?

The westerlies blow from the southwest so the water will move toward the northeast due to Coriolis deflection and flows around 45 degrees to the right of the wind direction.

What are the great current circuits in the world?

There are two in the northern hemisphere and four on the southern hemisphere. Five of them are geostrophic; North Atlantic gyre, South Atlantic gyre, the North Pacific gyre, the South Pacific gyre and the Indian ocean gyre.

Why are eastward flowing currents wider and flow more slowly?

They're not controlled by trade winds.

Why do water in gyres go strait without turning?

To turn right, the water would have to move uphill against the pressure gradient, but to turn left in response to the pressure gradient would defy the Coriolis effect.

14. Why do fisheries on South America's west coast decline—often dramatically—in El Niño years?

Upwelling within the nutrient-laden Peru Current is responsible for the great biological productivity of the ocean off the coasts of Peru and Chile. Although upwelling may continue during an ENSO event, the source of the upwelled water is nutrient-depleted water in the thickened surface layer approaching from the west (Figure 8.18). When the Peru Current slows and its upwelled water lacks nutrients, fish and seabirds dependent on the abundant life it contains die or migrate elsewhere.

Water within a western boundary current is usually ___ and often ___

Warm / Depleted of nutrients and incapable of supporting life.

Why do surface currents affect weather and climate?

Warm water flows to higher latitudes, transfers heat to the air and cools, moves back to low latitude and absorbs heat again. The combination of water flow and he transferred from and to water influences climate and weather

8. What is the relationship between surface currents and the climate of adjacent continents?

Warm water flows to higher latitudes, transfers heat to the air and cools, moves back to low latitudes, absorbs heat again, and the cycle repeats. The greatest amount of heat transfer occurs at mid-latitudes, where about 10 million billion calories of heat are transferred each second.

4. Why does seawater in most surface currents flow around the periphery of ocean basins? How is Coriolis effect involved?

Water flow in a gyre is dynamically balanced between the downhill urge of the pressure gradient and the uphill tendency of Coriolis deflection (see again Figure 8.7 and 8.13).

18. What is the general pattern of thermohaline circulation?

Water sinks relatively rapidly in a small area where the ocean is very cold, but it rises much more gradually across a very large area in the warmer temperate and tropical zones. The continual diffuse upwelling of deep water maintains the existence of the permanent thermocline found everywhere at low and mid-latitudes.

Eastern current boundaries are not ___ and ___ rarely form.

Well defined / eddies

Unlike rivers, ocean currents lack ___

Well defined banks.

What is the sixth gyre?

West Wind Drift / Antarctic Circumpolar Current. Technically not a gyre.

Where are the fastest and deepest geostrophic found?

Western boundaries of ocean basins.

6. Name a western boundary current. An eastern boundary current.

Western boundary currents (at the western edge of an ocean basin) include the Gulf Stream, the Kuroshio Current, and Brazil Current., Eastern boundary currents (at the eastern edge of an ocean basin) include the California Current, the Canary Current, and the Peru Current.

5. Compare and contrast western boundary currents to eastern boundary currents.

Western boundary currents tend to be hot, fast, and deep. Eastern boundary currents are cold, slow, and shallow.

How does upwelling influence weather

When blowing up the north along places like California coast causes offshore movement of surface water and subsequent coastal upwelling the overline air becomes chilled contributing to fog banks and cool summers

What forces circulates the oceans clockwise in the northern hemisphere and counter

clockwise in the southern hemisphere? - Surface winds, the suns heat, the Coriolis effect, and gravy.

What does the equatorial countercurrent do and why?

When the water hits the continents, its forced to go backwards.

What causes coastal upwelling

Winds from the north going along the west coast of a continent. water moved off shore by Ekman transport is a place by cool deep nutrient latent water

what happens in convergence zones? Caballing?

two water masses with the same density but different temperatures and salinities will mix and produce mass of greater density, this process is caballing