Essentials of Oceanography

Lesson 4 Introduction


The Global Thermostat. The Ocean-Atmosphere-Climate Connection

About Lesson 4

Map showing Great Ocean Conveyor Belt
Source: Broecker, 1991, in Climate change 1995, Impacts, adaptations and mitigation of climate change, UNEP and WMO, Cambridge press university, 1996

In this lesson, we have the ambitious task of tackling the heat distribution on Earth and it's role in dictating ocean circulation, atmospheric circulation, and Earth's climate.

By the end of this lesson you should have a deeper understanding of the role of the oceans and atmosphere in heat transfer on Earth, the structure of the oceans including surface water and deep water, thermo-haline circulation including patterns and the factors that drive flow, the Coriolis effect and Ekman transport, large-scale atmospheric circulation, oceanic gyres, and boundary currents in the ocean basins.

This figure incorporates many of the topics we will cover in Lesson 4. Note the Gulf stream in the North Atlantic and the sea-to-air heat transfer associated with it. Also note the three dimensional nature of ocean current flow (the conveyor), which includes warm surface currents and deep currents.

What will we learn in Lesson 4?

By the end of Lesson 4, you should be able to:

  • Describe the solar energy budget for Earth including variations with latitude of energy input and output.
  • Explain how heat is transferred from low to high latitudes by the oceans and the atmosphere.
  • Explain the roles of latent heat and sensible heat in energy transfer by ocean currents.
  • Describe the pattern of global winds and its relationship to heat transfer.
  • Describe the primary structure of ocean waters as a function of depth, including the changes in average temperature and salinity.
  • Explain the main factors that determine surface and deep ocean currents.
  • Explain the Coriolis effect, it's origin, and it's influence on global winds and ocean currents
  • Describe how the Coriolis effect and Ekman transport influence ocean surface currents
  • Describe the 'ocean conveyor' and it's role in global heat transfer and climate regulation
  • Use on-line resources to construct maps of ocean temperature and salinity

What is due for Lesson 4?

The chart below provides an overview of the requirements for Lesson 4. For assignment details, refer to the lesson page noted. See the Course Schedule (located in the Resources menu) for assignment due dates.

Lesson 4 Assignments
Activity 1: Pressure Belts page 1 Yes
Activity 2: Ocean Currents and Density page 4 Yes
Activity 3: Gyres and Surface Currents page 5 Yes


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