What is thermohaline circulation?
Thermohaline circulation is a global ocean circulation pattern that distributes water and heat both vertically, through the water column, and horizontally across the globe. As cold, salty water sinks at high latitudes, it pulls warmer water from lower latitudes to replace it. Water that sinks in the North Atlantic flows down to the southern hemisphere, skirts the Antarctic continent, where it is joined by more sinking water, and then crosses south of the Indian Ocean to enter the Pacific Ocean basin. There, the cold deep water rises to the surface, where heat from the tropical sun warms the water at the ocean’s surface and drives evaporation, leaving behind saltier water. This warm, salty water flows northward to join the Gulf Stream, traveling up the Eastern coast of the United States and across the Atlantic Ocean into the North Atlantic region. There, heat is released to the atmosphere, warming parts of Western Europe. Once this warm, salty water reaches the North Atlantic and releas
Identify these in your diagram. 6. How might a warming earth affect density currents? 7. Why are density currents important? 8. How would you expect climate to affect the salinity of seawater? 9. Design a model that would show how melting glaciers could affect ocean circulation. Analysis Answers: 1. Many times students will be able to see two different layers of water. In order to create a continuous current in the closed container, one would need to change the density of the water at one end of the container. This could be done by altering the temperature (using conduction bar or heat lamp at one end of container and salt water cube at the other). 2. Different for every lab group 3. The Antarctic Bottom water is our most dense water. This is due to the cold temperatures (-.5° Celsius) and the freezing water at the surface leaving the salt water behind. 4. Altering the amount of salt in the water can do this. Students should note the displacement of the other water in the container. If
What is a gyre? What are transverse currents? In what direction does Western-Boundary Currents flow? In what direction does Eastern-Boundary Currents flow? What is the Ekman spiral? What is upwelling? Why is there upwelling along the California coast? Would upwelling increase or decrease fish populations? Why? What is a water mass? How do they differ from other water masses? Are deep water temperatures and salinities in different oceans similar or very different? Is they are similar does that imply deep ocean circulation between ocean basins? Why? Give the depth range in meters for intermediate, deep, and bottom waters. What is thermohaline circulation? What is the typical velocity (in kilometers per day) of a deep ocean current? What is the North Atlantic Deep Water? Why does it form? What connection does it have with the Gulf Stream? What role does sea-ice play in the formation of the Antarctic Bottom Water? Is the Mediterranean Outflow Water more or less dense than Atlantic Ocean wa
Thermohaline circulation is a very slow and extremely deep movement of water in the oceans around the world. A complete cycle can take thousands of years to complete from start to finish, with the cycle contributing a great deal to the mixing of the world’s oceans. Thermohaline circulation appears to be linked to global climate and ocean health, as it mixes dissolved gases and minerals in the water and it may impact global temperatures as well. When broken into its component roots, thermohaline refers to the temperature (thermo-) and dissolved salts (-haline) in ocean water. These salts are known as halides. Temperature and halinity of the water has an impact on its density, and this triggers thermohaline circulation. The colder water is, the more dense it is, and the saltier the water is, the higher the density. Because of thermohaline circulation, the Atlantic Ocean is denser than the Indian and Pacific oceans, making it slightly lower. The cycle starts around the equator in the Paci
