1. ThermoHaline Circulation

2. What is Thermohaline Circulation?
Thermohaline circulation describes the slow deep-ocean movements of sea water around the world.
What is Thermohaline Circulation?

3. Thermohaline circulation begins in the Earth’s polar regions
Thermohaline circulation begins in the Earth’s polar regions. When ocean water in these areas gets very cold, sea ice forms.
The surrounding seawater gets saltier to accommodate the salt expelled by the sea ice.
The surrounding seawater becomes denser an sinks.
How does it happen?

4. Wind drives surface currents in the upper 100 meters of the ocean’s surface.
The deep-ocean currents are differences in the water's density because of temperature and salinity.
Currents

5. The salty sea water sinks and surface water is pulled in to replace the sinking water.
This surface water eventually becomes cold and salty enough to sink as well.
This initiates the deep-ocean currents driving the global conveyer belt.
Sinking?

6. Thermohaline circulation drives a global- scale system of currents called “global conveyor belt.”
The conveyor belt begins on the surface of the ocean near the pole in the North Atlantic where cold temperatures and salt cause water to sink.
The deep water moves south, between the Americas and Europe and Africa.
The currents travels around the edge of Antarctica, where the water cools and sinks again. This recharges the belt.
Global Conveyor Belt

7. The currents travels around the edge of Antarctica, where the water cools and sinks again. This recharges the belt.
The current turns northward and splits into two section.
One section moves to the Indian ocean, and the other into the Pacific ocean.
Global Conveyor Belt

8. The two sections that split off warm up and become less dense as they move toward the equator.
The water rises to the surface in a process called upwelling. The water then looks back southward and westward to the south atlantic.
The water eventually returns to the north Atlantic, where the cycle begins again.
Global Conveyor Belt

10. The conveyor belt moves at much slower speeds (a few centimeters per second) then the wind- driven or tidal currents (tens of hundreds of centimeters per second).
It is estimated that any given cubic meter of water takes about 1,000 years to complete the journey along the global conveyor belt.
The belt moves an immense volume of water. More than 100 times the flow of the Amazon river.
Rate of Movement

11. The conveyor belt is also a vital component of the global ocean nutrient and carbon dioxide cycles.
Warm surface waters are depleted of nutrients and carbon dioxide, but they are enriched again as they travel through the conveyor belt as deep or bottom layers.
The base of the world’s food chain depends on the cool, nutrient-rich waters that support the growth of algae and seaweed.
Importance?