Deep Ocean Currents Lecture Notes

Introduction

• Previous video discussed shallow ocean currents driven by wind.
• Deep ocean currents are driven by water density differences.
• Density differences are related to variations in temperature and salinity.

Key Concepts

• Density and Salinity:
  • High-density occurs in areas with cold and salty water.
  • Sinking water due to high density drives deep ocean circulation.

Saltiest and Coldest Ocean Areas

• Antarctica and Greenland:
  • Most dense water found near these regions.
  • Antarctic Bottom Water:
    • Salty due to ice formation.
    • Deepest and most dense water on Earth.
  • North Atlantic Deep Water:
    • Salty due to cooling and evaporation.
    • Most prolific in volume.

Thermohaline Circulation

• Drives deep ocean currents based on temperature (thermo) and salt (haline).

• Deep Water Formation Locations:

  1. Near Antarctica.
  2. Near Greenland.

• Circulation Process:

  • Water sinks from the ocean surface to the bottom.
  • Travels along various paths before gradually rising and warming.

Ocean Conveyor Belt

• Side View Diagram:
  • Atlantic Ocean shown with Greenland on the left and Antarctica on the right.
  • Cold water near Greenland forms North Atlantic Deep Water.
  • Cold water near Antarctica forms Antarctic Bottom Water.
  • Antarctic Bottom Water is the densest and found at the ocean bottom.
  • North Atlantic Deep Water layers above it.
  • Intermediate and warm tropical surface waters layer above.

Speed of Deep Ocean Currents

• Average speed: 0.03 to 0.06 km/h.
• Much slower than surface currents like the Gulf Stream (3 km/h).
• Implications:
  • Deep ocean currents are 100 times slower than surface currents.
  • Takes hundreds of years for water to complete the cycle from sinking to rising.
  • Deep ocean properties are isolated and do not easily mix with the atmosphere.