Southern Hemisphere Studies, Part 1

1. Southern Hemisphere Studies, Part 1 Earth2Class Workshops For Teachers at the Lamont-Doherty Earth Observatory 15 Nov 2003

2. Martin Visbeck:What Can Ocean Temperatures Tell Us about Climate in the Southern Hemisphere? Michael Studinger: Uncovering the Secrets of Lake Vostok

3. For those of us in the US and most of the Northern Hemisphere, the Southern Hemisphere is largely “Terra Incognito” With all our understanding of the globe, we tend to think of the Southern Ocean and surrounding land masses merely as the bottom half of maps. Perhaps another view will start to show more about this interesting portion of our planet: http://www.ngdc.noaa.gov/mgg/image/predict.gif

4. Our focus today will be on the Southern Ocean currents and Antarctica • I’ll provide a little more introduction to the Antarctic part of our program later in these slides • Looking now at the ocean currents, we usually think of them as shown in the next slide

5. http://www.windows.ucar.edu/tour/link=/earth/Water/images/Surface_currents_jpg_image.htmlhttp://www.windows.ucar.edu/tour/link=/earth/Water/images/Surface_currents_jpg_image.html

6. What did you notice? • The Southern Ocean is the only area of the world with flow uninterrupted by land • The general movement is west-to-east • There are connections with other surface currents to the north and poleward • These involve both wind-driven surface currents and density-driven deeper circulations

7. Connections between Surface and Deep-Sea Currents In the past few years, greater under-standings have developed concerning the elaborate interactions btween the wind-driven surface patterns and the thermo-haline (temperature and salinity) deeper flows. One model of this is the “Ocean Conveyor Belt, depicted in the next slide:

8. http://www.grida.no/climate/vital/32.htm

9. Much attention has been given to this model, especially speculations about what might happen if it changes LDEO’s Wally Broecker, who helped devise this model, recently considered the impact on climate that might ensue if the conveyor belt slowed or stopped http://faculty.washington.edu/wcalvin/teaching/Broecker99.html

10. Returning to our Southern Hemisphere focus, let’s consider a model of what happens as the ocean currents flow around the world. Of special consideration are places where land masses constrict their movements, such as Drake’s Passage between South American and Antarctica

11. http://www.nsf.gov/pubs/1996/nstc96rp/sb6.htm Warm circumpolar water passes through the Drake Passage and flows eastward in the Antarctic Circumpolar Current (red arrow). Some of the flow is diverted southward into the Weddell Gyre and becomes more dense, sinks, and flows out near the bottom (blue arrow). The inset illustrates the two processes that increase the density: lowering the temperature by giving up heat to the atmosphere, and raising the salinity of the remaining sea water by forming nearly salt-free ice in the very cold environment.

12. The circulation patterns in the flow around Antarctica play major roles in global air-sea exchanges http://www.glacier.rice.edu/oceans/4_antsurfwater.html

13. Water Masses • Exchanges between the atmosphere and oceans around Antarctica are significant factors in forming the “water masses” that participant in the density-driven deep-sea circulation • The American Meteorological Society has a teacher-training guide and other materials that explain more about this

14. ARGO Floats • One of the most useful systems now used to understand water masses and ocean flow is the ARGO array http://www-argo.ucsd.edu/

15. How to Access ARGO Data • You can track ARGO floats at http://62.161.32.97/website/ArgoMap/viewer.htm?Title=Argo%20Real%20Time%20Status • You can also access ARGO data through the AMS Water in the Earth Systems site http://64.55.87.13/amsedu/WES/home.html • This links you to the University of Washington data site http://flux.ocean.washington.edu/argo/

16. Martin Visbeck will explain more about the Southern Ocean and its impact on global climate. We are also privileged to have Michael Studinger discuss some of his research about Antarctica, especially in Lake Vostok.

17. Lake Vostok lies buried under 4 km of ice. Researchers from LDEO and elsewhere are trying to uncover its secrets. Here’s a recent news story about their efforts: http://www.earthinstitute.columbia.edu/news/story3_2_01.html

18. Lake Vostok Animation Robin Bell, Michael Studinger, and colleagues have created an animation about Lake Vostok: http://www.earthinstitute.columbia.edu/news/vostok/vostok.swf

19. Dr. Studinger’s web pages about Lake Vostok may be accessed through http://www.ldeo.columbia.edu/~mstuding/vostok

20. Antarctic seas also teem with interesting lifeforms and ecosystems Dr. Sam Bowser was the 2003 Keynote Speaker at the 108th STANYS Conference Dr. Bowser’s research about foraminifer and other life in Antarctic waters is available at http://members.global2000.net/bowser/

21. To end this portion of our introduction, I draw your attention to some of the resources available in connection with today’s program http://www.earth2class.org/k12/w3_f2003/resources.htm These include some interesting activities developed for children at the LDEO Open House.