General Circulation Oceans

Question 1

Ocean Circulation

Answer 1

• Heat transport from tropics ➙ poles
• Some concepts…
• mixed layer
• ocean gyres
• wind-driven circulation
• thermohaline circulation

Question 2

Subtropical ocean gyres

Answer 2

Subtropical gyres circle areas beneath regions of high atmospheric pressure. These are placid ocean areas thousands of kilometers in diameter. Unlike coastal zones, these central regions are relatively stable. The ocean water generally stays in one place while the currents of the gyre circulate around it.

Question 3

Wind-driven circulation

Answer 3

Wind driven circulation describes the process in which winds moving along the surface of the ocean push the water in their direction and create currents near the surface. These winds are subject to the Coriolis Effect, which creates their motion based on the rotation of the earth.

Question 4

Surface ocean currents

Answer 4

Large-scale surface ocean currents are driven by global wind systems that are fueled by energy from the sun. These currents transfer heat from the tropics to the polar regions, influencing local and global climate.

Question 5

Deep-ocean Circulation

Answer 5

• Thermohaline circulation
• density-driven sinking at high latitudes
  ‣ cold
  ‣ brine (salt) rejection
• Density (1) temperature => cold = denser
• (2) salinity: averages 35 ‰ => 3.5% more dense that
  freshwater
• Locations: N. Atlantic and Antarctica (not N. Pacific… not cold enough)
• Deep water masses
• North Atlantic Deep Water
• Antarctic Bottom Water
• Antarctic Intermediate Water
• Mediterranean Outflow Water

Question 6

: Deep Atlantic circulation

Answer 6

However, ocean currents also flow thousands of meters below the surface. These deep-ocean currents are driven by differences in the water’s density, which is controlled by temperature (thermo) and salinity (haline). This process is known as thermohaline circulation.

Question 7

Return Flow

Answer 7

• Reponse time ~1000 years
• time for water to sink and re-emerge
• How does water return to the surface?
• upwelling
  ‣ coastal upwelling
  ‣ equatorial upwelling

Question 8

Equatorial upwelling

Answer 8

The rising of water along the equator from about 200 m to the surface. It occurs in the Atlantic and Pacific Oceans where the Southern Hemisphere trade winds reach into the Northern Hemisphere, giving uniform wind direction on either side of the equator.