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Earth Institute News

posted 10/25/04

Contact: Mary Tobin
845-365-8607 or mtobin@ldeo.columbia.edu

Reports From the Field

The Anslope Expedition: Battling Rough Seas

October 25 , 2004
Dr. Gerd Krahmann aboard the R/V Nathaniel B. Palmer...

65 S 47.6
142 E 34.1
95% ice cover, 0.5m thick
air temperature: -12C
sea surface temperature: -1.85C
10kn winds from the south
cloudy

This is the first report from the field from the third ANSLOPE cruise on board the R/V Nathaniel B. Palmer. Nearly two weeks ago we left Lyttelton, New Zealand to steam towards Antarctica. (read previous AnSlope Report and previous CORC/ARCHES Report From the Field.)

It took us about a week to reach the ice. As on previous cruises to these southern waters we had to cross the windiest and roughest part of the world's oceans. With everything safely tied to tables, walls and floors the huge waves were not able to cause any problems for our equipment. Unfortunately, this could not be said for the stomachs of some of us.

These stomachs got the prospect of additional trouble shortly before the cruise, when we were told that the ship would have to return to harbor after about 30 days at sea. Originally, we had planned to stay out at sea for the whole 60 days of ship time dedicated to our project. That means that we have to cross the rough part of the ocean not twice (down to Antarctica and back) but four times.

This development had quite an impact on our plans. Though we are here in the southern hemisphere's spring season, the ice from last winter has not yet melted. In fact it is now just one or two months after the ice had reached its maximum winterly extent. Our original work area at the continental shelf break of the Ross Sea lies about 400 nautical miles (440 miles) inside the ice. It would likely take more than four days to cross. That means that from a 30-day cruise leg out at sea, only 6 days would be spent in the work area.

Palmer Station

The R/V Nathaniel B. Palmer docked in Lyttelton, New Zealand.

We thus decided to divert to an area further west in which we could observe similar processes as in the Ross Sea but which is located only 50 nautical miles within the ice. We hope that by the time of the second cruise leg the ice in the Ross Sea has melted enough to try to get to the original work area.

Five days ago we arrived off the George V Coast, our new work area. Since then we have been working round the clock measuring physical and chemical properties of the ocean over the continental slope. The data we are collecting will help us to understand what exactly happens when dense water that is formed further on the continental shelf spills over the continental shelf break into the deep part of the Southern Ocean. Later during the cruise we will report more on this.

Apart from participants in the ANSLOPE project we also have wildlife and sea ice observers on board. They are studying possible connections between sea ice type and wildlife. We will report more on them in our next report from the field.