Quiz 29 oct Flashcards
What is a mass flow of ocean water driven by?
wind and gravity
What is occuring at the friction depth?
At the friction depth, water will flow in the opposite direction from the surface current
What are the six great current circuits in the ocean and which ones are geostrophic gyres?
There are 6 great current circuits in the ocean: 5 of them are geostrophic gyres:
North and South Atlantic gyres,
North and SouthPacific gyres
and Indian Ocean gyre.
The last one is called the West Wind Drift
What are geostrophic currents?
The currents that form a geostrophic gyre. WET
1-Western boundary
2-Eastern boundary
3-Transverse
What are the characteristics of Western boundary currents?
• Fast, deep currents that move warm water poleward in each of the gyres
-Great volume of water, measured in sverdrups (sv) = 1 million cubic meters per second
- Water in western boundary currents (WBC) can move for long distances within well-defined boundaries
- WBC form meanders as they flow poleward
- Eddies
What are the characteristics of Eastern boundary currents?
- Eastern boundary currents
- Shallow, broad, with ill-defined boundaries
- Carry cold water toward the equator • Shallow and broad (up to 1000 km)
- Eddies tend not to form
- Carry much less water that WBC
What are eddies? What is the difference between cold-core eddies and warm-core eddies?
eddies: turbulent rings formed by connected looping meanders. They trap cold or warm water in their centers and separate from the main flow
• 2 types: cold-core Eddies (rotate counterclockwise) and warm-core Eddies (rotate clockwise)
How much of the North Atlantic may consist of old cold-core eddies?
1⁄4
What is wind-induced vertical circulation?
Vertical movement induced by wind-driven horizontal movement of water:
What is upwelling?
- Upwelling: upward motion of water
* Brings cold, nutrient-rich water toward the surface
What is downwelling?
- Downwelling: downward motion of water
* Supplies the deeper ocean with nutrients and dissolved gases
What is Equatorial upwelling?
when water moving on either side of the Equator is deflected slightly poleward (Coriolis effect) and replaced by ascending nutrient-rich deeper water
What is coastal upwelling?
Coastal upwelling: occurs when this surface water is replaced by water rising from the bottom along the shore (coast)
What is thermohaline circulation?
Thermohaline circulation: Movement of water driven by differences in density (temperature and/or salinity) involving the whole ocean
What does the flow of water in the conveyor belt distribute?
• The flow of water in the conveyor belt distributes dissolved gasses, solids, nutrients and larvae of different organisms among ocean basins
What are the different ways currents are studied?
SDAT
• Surface currents traced with drift bottles or drift cards
-Drifting Buoys can be tracked continuously by radar or radio direction finders (or gps)
• Argo system floats: autonomous drifting sensors that move vertically (up to 2000 m) measuring temperature and conductivity in their path. Data uploaded to a satellite to calculate salinity and other parameters.
-Tracking movement of chlorofluorocarbons (CFCx)
What is the greenhouse effect?
• The Greenhouse effect is a natural phenomenon which allows keeping Earth’s surface at a habitable average temperature, which was 14oC before the industrial revolution
is a process that occurs when gases in Earth’s atmosphere trap the Sun’s heat. This process makes Earth much warmer than it would be without an atmosphere.
How are currents classified & describe each one
STG
• Surface currents
• Wind-driven movements of water at or near the ocean’s surface
Thermohaline currents
• Slow, deep currents (depending on density differences caused by variations in temperature and salinity) that affect the vast bulk of seawater beneath the pycnocline
• Geostrophic currents: the currents (with different characteristics) that form a geostrophic gyre
Explain the Ekman spiral
Ekman spiral: deflection of surface currents caused by wind in which the flow direction rotates as one, moves away from the initial contact surface boundary.
What are gyres?
Gyre: Current flow around the periphery of an ocean basin
Types of water masses?
SCIDB
- Surface water: up to 200 m deep
- Central water: to the bottom of the main thermocline (below 1000 m in mid- latitudes)
- Intermediate water: up to 1500 m deep
- Deep water: between IW and up to 4000 m. Not in contact with the bottom
- Bottom water: in contact with the sea floor
