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OCN 201 Eighth Reading Discussion Questions

Ocean Circulation

Trujillo and Thurman - Chapter 7

7.5 What Deep-Ocean Currents Exist? (p. 222)

1. Which percentage of the ocean's currents are deep-ocean (thermohaline) currents?

2. Why are thermohaline currents called density-driven currents?

3. Give a typical speed for thermohaline currents in km/year.

4. Define thermohaline circulation. (Also see p. 533)

Origin of Thermohaline Circulation

5. Which factor primarily controls seawater density?

6. Where do most thermohaline currents originate?

7. Explain why a thermohaline current's temperature and salinity do not change significantly once the water body sinks below the surface.

8. Use the T-S diagram in fig. 7.26 to give the name and the density in g/cm3 of the densest water in the Atlantic Ocean.

9. Use the T-S diagram in fig. 7.26 to give the temperature and salinity of the NADW.

10. Use the T-S diagram in fig. 7.26 to explain why the AABW is more dense than the NADW.

11. Explain why a thermocline does not form in the high latitudes. (Also see fig 7.27)

Sources of Deep Water

12. Describe the formation of the AABW. (Also see figs. 7.27 and 7.28, and the Antarctic Bottom Water definition on p. 517)

13. Where does the NADW form? (Also see figs. 7.27 and 7.28, and the North Atlantic Deep Water definition on p. 528)

14. Use fig. 7.27 to contrast the AABW and NADW flow directions in the Atlantic Ocean.

15. Explain why the NADW flows over the AABW. (Also see fig. 7.27)

16. Which water body forms at the Antarctic Convergence? (Also see fig. 7.27)

17. Use fig. 7.27 to give the AAIW flow direction.

18. Use the AAIW's definition on p. 517 to give the current's depth.

19. Explain why substantial vertical mixing occurs in the high latitudes but not in the low latitudes. (Also see fig. 5.27)

20. Describe (Oceanic) Common Water formation. (Also see p. 528)

Worldwide Deep-Water Circulation

21. Give possible deep-water upwelling mechanisms.

Conveyer-Belt Circulation

22. Use fig. 7.28 to give the flow direction for deep-water circulation.

Dissolved Oxygen

23. Explain why deep water contains dissolved oxygen.

24. Explain why global warming could result in mass extinctions in the deep-ocean ecosystem.

A Case Study: The Mediterranean Sea (p. 322)

25. Explain why circulation between the Mediterranean Sea and the Atlantic Ocean is restricted. (Also see fig. 11.12)

26. Describe the circulation in the Mediterranean Sea. (Also see fig. 11.12)

27. Use the T-S diagram in fig. 7.26 (p. 223) to explain why the MIW is less dense than the NADW and the AABW, despite its high salinity.

28. Which factor controls the Mediterranean Sea's density structure?

29. Give the MIW's depth in the Atlantic Ocean.