Mary Tobin

Reports from the Field

The Antarctic CORC/ARCHES Expedition,
April 5 through May 8, 2003

April 16, 2003

A dirty iceberg, containing soil from the times when it, as a glacier, flowed of the landmasses of Antarctica. It is about the size of a house.

Latitude: 62S 07.5
Longitude: 51W 19.7
Sky: clear
Wave height: 0.1m
Air temperature: -1C
Wind Speed: 10kn

Just a quick note from a gorgeous day. We woke up to blue skies and no waves at all. The entire horizon was covered in icebergs, ranging in size from minivan to several miles long. To see them like this is quite normal for the northern Weddell Sea, though their location is further north than we have seen them in the past 4 years. But then this is the latest time in the year that we have been here.

Pancake ice.

Right now we are traveling through brash ice, which consists of ice crystals lumped together in the early stages of the freezing process. When waves push this brash ice around it tends to form pieces that look like pancakes, hence the name pancake ice. When it freezes even more, these pancakes start to stick together and form a solid sea ice cover.

Icebergs come from the southern Weddell Sea where huge ice shelves are located. Different from the sea ice, which, in Antarctica, is formed in winter and melts over the summer, icebergs are formed over thousands of years on land and slowly flow as glaciers towards the ocean where they then break off and are moved around by ocean currents. A typical iceberg has a height above water of 20m, an area of about a city block, and reaches 150m deep into the ocean. We are thus seeing only small fractions of the bergs.

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April 15, 2003

CORC/ARCHES Expedition
Afternoon, Tuesday, April 15, 2003, from Dr. Gerd Krahmann

Aboard the R/V LAURENCE M. GOULD...


Hauling in the net after it has been trawled along the sea floor for about one hour.

Latitude: 62S 51.4
Longitude: 59W 6.3
Sky: overcast
Wave height: 2m
Air temperature: 0.5C
Wind Speed: 20kn

We are finally on the way to our research area. This evening we will do a first test of one of the main instrument packages to be used - a CTD, which stands for conductivity-temperature-depth. It allows us to measure the salinity and temperature of the sea water from ocean surface to bottom. At the test station, the water depth will be 2000m but we hope to get to places where it is 4000m deep. The CTD package is attached to a large steel frame which also holds 24 plastic cylinders, each with a volume of 10 liters. The whole thing is lowered from the ship on a special steel wire and we continuously record data during descent and ascent. The data link through the wire allows us to close the plastic cylinders to take water samples at different depth that we then analyze on board or at home for traces of chemicals and isotopes.

A skate and other bottom dwelling fish caught during the trawl.

Before my next report, when I can report on work begun for our CORC/ARCHES project, I will give you an account of our colleague's fish-biology research over the past few days.

On April 11, we left Palmer Station to head for an area north of Anvers Island. Within two nights and one day, the group managed to catch a good number of fish using two different methods: a type of trap similar to what is used in Alaska to fish for crabs, and a small net that was trawled over the sea floor. The catch included several different kinds and sizes of so-called icefish, one skate, and a number of fist-sized octopods. As the biologists want to keep the fish alive, they are carefully handled on deck and in aquariums to ensure their survival.

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