Lecture 17: Oceans Part 1 Flashcards
-Geography of the Oceans -Physical and Chemical Properties of the Ocean -Deep and Shallow Ocean Currents -Southern Oscillation/El Nino
What is salinity?
Measures the proportion of dissolved ions in the ocean water.
What are the primary constituents?
Chloride, sodium, sulfate, magnesium, calcium, potassium, and bicarbonate
What are the sources of ions in the ocean?
- Dissolved load delivered from land with rivers
- Submarine volcanic activity
- Primarily mid-ocean ridges
What are sinks of ions in the ocean?
- Precipitation of minerals
- Sequestration by living organisms to produce shells
- Sorption to clay minerals
- Removed in sea spray
- Reactions with basaltic seafloor rocks
What are the variations in the ocean water with depth?
- Temperature decreases with depth, because saline water is denser and sinks
- Salinity increases with depth, because saline water is denser and sinks
- Seawater density increases with depth both due to decreasing temperature, increasing salinity, and compression of liquid water itself, with depth.
What are ocean currents caused by?
- Air currents interacting with the surface of the oceans
- The sinking of denser water
- Effects resulting from the rotation of the Earth
What is the conveyor belt in the Atlantic Ocean?
The freezing of seawater at the margins of the Antarctic and in the far North Atlantic generates cold, saline dense water that sink.
As NADW approaches Antarctica, it rises up to the surface against the ABW below.
-Some of this water is carried by currents northward, until it interacts with warmer, less dense water and sinks to create the Antarctic Intermediate Water (AIW)
What is the thermohaline circulation the result of?
Density-driven movement of water in the oceans.
-This deep circulation network plays a critical role in controlling global climate.
What is the Coriolis Effect?
The surface of solid Earth is rotating about its vertical axis to some degree, everywhere except the equator:
- Counterclockwise (CCW) in the northern hemisphere
- Clockwise (CW) in the southern hemisphere
Objects moving in a straight line appear to curve relative to solid Earth beneath them.
- Right in the northern hemisphere
- Left in the southern hemisphere
Where does upwelling occur?
Where the transport direction is offshore. Nutrient-rich water brought up.
Where does downwelling occur?
Where the transport direction is onshore.
What is an El Nino year?
The atmospheric pressure difference between the west Pacific and the east Pacific weakens, causing trade winds to slow or reverse.
-Without trade winds to move upwelling water, upwelling stops.
How does the Coriolis Effect cause ocean circulation in the northern hemisphere?
Wind-driven currents are notably clockwise of the actual wind direction.
Deeper currents are progressively rotated CW because of slower water velocity.
What is a normal year for surface currents?
Surface currents off the coast of South America move northward, and Ekman transport causes upwelling and movement of water offshore.
