SIO 210 Talley Topic 6: Global and southern ocean circulation

Lynne Talley, 1997
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Reading and study questions

Reading (on reserve):

Tomczak and Godfrey:
chapters 6, 11 (pp 193-195, 198-201, 208-220), 12
or Pickard and Emery: chapter 7.32, 7.63, 7.65, 7.7, 7.8

Reid, J.L. and R. J. Lynn, 1971. On the influence of the Norwegian-Greenland and Weddell seas upon the bottom waters of the Indian and Pacific oceans. Deep-Sea Res., 18, 1063-1088.

Schmitz, W. J., 1995. On the interbasin-scale thermohaline circulation. Rev. Geophys., 33, 151-173.

Look through
Geosecs atlases: Pacific, Atlantic and Indian
Gordon and Baker atlas: Southern Ocean
Wyrtki atlas (Indian)

Study questions

1. What are the basic dynamics assumed to drive much of the deep circulation? What direction would you expect the interior deep flow to go if the ocean were flat-bottomed (vertical sides) with isolated sources of deep water?

2. Locate the Antarctic Intermediate Water in all oceans using its most common characteristic. (Look in the Geosecs atlases or at various vertical sections.) How far north is it easily discernible?

3. Does Weddell Sea bottom water get very far from its source in the Weddell Sea? Does the "Antarctic Bottom Water" found in the North Atlantic come from the deep or bottom waters around Antarctica?

4. Are there subpolar (cyclonic) wind-driven "gyres" in the southern hemisphere?

5. Why are the properties in the three southern hemisphere oceans fairly similar compared with those in the northern hemisphere?

6. The Gordon/Broecker "conveyor belt" for the North Atlantic Deep Water cell shows a return flow of warm water across the Indian Ocean and into the North Atlantic. What is the source of this warm water? By what property is it easily recognized in the Indian Ocean?

7. What are the highest and lowest silica regions at mid-depth? (What regions produce water with low and what with high silica?)

8. Where are the saltiest and the freshest intermediate and deep waters found? (e.g. look at different isopycnals and note the extremes)

9. Draw a schematic vertical profile of zonally-integrated meridional mass transport across a subtropical latitude in each ocean. Label which water masses are responsible for northward and southward transport. What is implied about upwelling or deep water formation in each basin? What is the sign of the associated net heat transport (total - vertically integrated)?

Additional sources for viewgraphs and discussion:

Gordon, A.L., 1986. Interocean exchange of thermocline water. J. Geophys. Res., 91, 5037-5046.

Gordon, A.L. and T. N. Baker, 1986. Southern Ocean Atlas, International Decade of Ocean Exploration, Amerind Publishing.

Lynn, R.J. and J.L. Reid, 1968. Characteristics and circulation of deep and abyssal waters. Deep-Sea Res., 15, 577-598.

Mantyla, A. and J.L. Reid, 1983. Abyssal characteristics of the World Ocean waters. Deep-Sea Res., 30, 805-833.

Mantyla, A.W. and J. L. Reid, 1995. On the origins of deep and bottom waters of the Indian Ocean. J. Geophys. Res., 100, 2417-2439.

Reid, J.L., 1981. On the mid-depth circulation of the World Ocean. In Evolution of Physical Oceanography, MIT Press, 70-111.

Rintoul, S., 1991. South Atlantic Interbasin exchange. J. Geophys. Res., 96, 2675-2692.

Roemmich, D.L. and T. McCallister, 1989. Large scale circulation of the North Pacific Ocean. Prog. in Oceanography, 22, 171-204.

Roemmich, D. and C. Wunsch, 1985. Two transatlantic sections: meridional circulation and heat flux in the subtropical North Atlantic Ocean, Deep-Sea Res., 32, 619-664.

Sverdrup, Fleming and Johnson, 1942. The Oceans, chapter 15

Talley, L. D., 1996. Antarctic Intermediate Water in the South Atlantic. In: The South Atlantic: Present and Past Circulation. Wefer, Berger, Siedler and Webb, eds., Springer-Verlag, in press.

Toole, J. M. and B.A. Warren, 1993. A hydrographic section across the subtropical South Indian Ocean. Deep-Sea Res., 40 , 1973-2019. (vertical sections and transport estimates at 32S).

Worthington, L.V., 1981. The water masses of the world ocean: some results of a fine-scale census. In Evolution of Physical Oceanography, MIT Press, 42-69.

Warren, B.A., 1981. Deep circulation of the World Ocean. In Evolution of Physical Oceanography, MIT Press, 6-41.

Wunsch, C., D. Hu and B. Grant, 1983. Mass, heat, salt and nutrient fluxes in the South Pacific Ocean. J. Phys. Oceanogr., 13, 725-753.

Wust, G., 1935. The stratosphere of the Atlantic Ocean. Translated by W.J. Emery, Amerind, 1978.

Wyrtki, K., 1971. Oceanographic Atlas of the International Indian Ocean Expedition. National Science Foundation, lots of pages.