ocs 2007 midterm2 (test 2)

What are the two types of ocean circulation?

Wind-driven circulation and thermohaline circulation

What drives wind-driven circulation?

Wind blowing at the sea surface.

What depth does wind-driven circulation affect?

Approximately the top 1000m of the ocean.

What drives thermohaline circulation?

Density differences caused by temperature and salinity variations.

Where do water mass characteristics form?

At the sea surface due to evaporation, precipitation, ice forming, and melting

How does the Coriolis force affect surface water movement?

It initially moves in the wind direction but is deflected 45° to the right in the Northern Hemisphere.

What is the Ekman spiral?

A pattern where current directions rotate clockwise (right) with depth and decrease in speed.

What is the average flow direction in the surface mixed layer (~100m)?

90° to the right of the wind in the Northern Hemisphere.

What is geostrophic adjustment?

The process of balancing sea level slopes and the Coriolis force, resulting in geostrophic currents.

How can geostrophic currents be computed?

by using satellite altimetry to measure sea level slopes.

What are subtropical gyres?

Large ocean circulation systems located around 30°N and 30°S.

What winds drive subtropical gyres?

Westerly winds in the northern half and easterly trade winds in the southern half.

How do subtropical gyres affect sea level?

They create a sea level high at the center, about 1m higher than the periphery

What direction do subtropical gyres circulate in each hemisphere?

Clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

What are western boundary currents?

Strong, narrow, fast-moving currents flowing away from the tropics (e.g., Gulf Stream, Kuroshio Current).

What are eastern boundary currents?

Weak, broad, slow-moving, and cooler currents (e.g., California Current, Canary Current).

What is the Antarctic Circumpolar Current (ACC)?

The largest transport current driven by strong westerly winds north of Antarctica.

What causes coastal upwelling?

When Ekman transport moves surface water away from the coast, bringing deeper, nutrient-rich water to the surface.

What causes coastal downwelling?

When Ekman transport moves surface water toward the coast, causing surface water to sink.

How do winds affect the Louisiana coast?

Easterly winds cause downwelling and flooding, while westerly winds cause upwelling and lower sea levels.

What is equatorial upwelling?

The process where trade winds cause surface water to move away from the equator, bringing nutrient-rich water up.

What are oceanic eddies?

Rotating water masses that mix water, heat, and nutrients.

What are warm-core eddies?

Anticyclones rotating clockwise in the NH with high sea surface height and downwelling.

What are cold-core eddies?

Cyclones rotating counterclockwise in the NH with low sea surface height and upwelling.

What is the Gulf Stream's role in eddy formation?

It forms warm-core rings north of the current and cold-core rings south of it.

What is the Loop Current?

A strong current in the Gulf of Mexico that generates large warm-core eddies.

How are ocean currents measured?

In Sverdrups (Sv); 1 Sv = 1 million cubic meters of water per second.

What is the thermohaline circulation?

The deep ocean circulation driven by temperature and salinity differences.

What percentage of ocean volume is part of the thermohaline circulation?

About 90%.

what is Antarctic Bottom Water (AABW)?

The densest water mass formed by freezing near Antarctica.

Where does North Atlantic Deep Water (NADW) form?

In the Norwegian and Labrador Seas.

What is Antarctic Intermediate Water (AIW)?

A mid-depth water mass that moves northward.

What is the Mediterranean Outflow?

Very salty water flowing out of the Mediterranean into the Atlantic.

What is the Great Ocean Conveyor?

The global thermohaline circulation moving water through all major ocean basins.

How long does it take for NADW to travel to the North Pacific?

Approximately 1000 years.

What is the salinity trend of the major oceans?

The North Atlantic is the saltiest, the North Pacific is the freshest, and the Indian Ocean is in between.

How does abnormal polar warming affect circulation?

It can slow down the Great Ocean Conveyor, leading to climate changes.

How is water mass age determined?

Using man-made tracers like CFCs and radioactive isotopes like tritium.

What is the average temperature of ocean water?

Approximately 3.5°C.

What are the two types of flow measurements?

Eulerian (fixed location) and Lagrangian (moving with currents).

What kind of measurement does a rubber duck or shoe in the ocean represent?

Lagrangian measurement.

How are temperature and salinity measured at depth?

Using a CTD (Conductivity, Temperature, and Depth) instrument.

What are the strongest currents in the Gulf of Mexico?

The surface currents, especially the Loop Current.

What happens when NADW meets AABW?

NADW rides above AABW due to its lower density.

Where does AIW originate and how does it move?

Forms north of Antarctica, sinks to intermediate depths, and moves northward.

What is the impact of Mediterranean Outflow on the Atlantic Ocean?

It increases salinity in the North Atlantic.

How does the Great Ocean Conveyor contribute to the global freshwater budget?

It returns excess freshwater from the North Pacific to the North Atlantic to maintain balance.

What is a covalent bond?

A chemical bond formed when two atoms share electrons.

How does a covalent bond relate to ocean chemistry?

Covalent bonds help form molecules like water (H₂O), which is essential in oceanic processes.