Plumbing the Southern Ocean the Southern Ocean Contains Only about 10 Percent of the World's Ocean Water, but Scientists Are Discovering That It Has a Vital Role in Regulating the Earth's Climate and the Temperature of the World's Oceans Series: POINTS OF THE COMPASS. First of Three Articles Appearing Today

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CAPT. Ewald Brune knows the moods of the Southern Ocean.

"It can be as flat as a millpond or as stormy as a hurricane," says the veteran of 12 years of Southern Ocean voyaging. And, when it's in a rage, he admits, "It's the worst weather in the world."

Fisherman Malcolm Hart of the village of Strahan, on Tasmania's west coast, says an oil rig exploring off Tasmania's west coast had barrels swept off its deck by high seas. The deck was 90 feet above the surface of the ocean. Mr. Hart says a research buoy off the coast has recorded swells of up to 108 feet.

"Oh, you have to watch the weather," says Mr. Hart, who has fished the Southern Ocean for 30 years.

During the winter, about a third of the Southern Ocean is covered by sea ice as Antarctica's extent doubles from its summer size. The ice can pose even more dangers than the waves. This year, South African sailor John Martin had to abandon his $1 million sailboat after hitting a "growler," a broken-up iceberg, in the Southern Ocean.

The Southern Ocean, containing about 10 percent of the world's ocean water, covers less area than the Indian, Atlantic, or Pacific Oceans, each of which it joins. But scientists are now discovering that the Southern Ocean is an integral part of the earth's circulation and climate system.

"It is like an oceanic conveyor belt where you have cold and saline antarctic waters sinking to the bottom. This cold water then flows north well into the northern hemisphere where it 'upwells' and you have warmer water flowing south," says Harvey Marchant, a principal research scientist at the Australian Antarctic Division, based in Hobart. This, in effect, regulates the temperature of the world's oceans.

"So even though it is only 10 percent of the world's oceans, it has a much larger effect," says Dr. Marchant.

Unlike the Arctic Ocean, which is not very deep and virtually surrounded by land, the Southern Ocean is deep, surrounding a continent the size of Australia. The Arctic is less saline since it is fed by large rivers in North America and Asia.

In addition, the Southern Ocean has the world's largest currents. Even though they only move at one to two knots, they are massive, says John Church, a scientist at the Commonwealth Scientific and Industrial Research Organization's (CSIRO) Division of Oceanography. He estimates the Southern Ocean currents move about 130 million cubic feet of water per second. By way of comparison, all of the world's rivers combined carry 1 million cubic feet of water per second.

This September scientists from the Antarctic Division and CSIRO will board the 18-month-old research vessel Aurora Australis to try to better understand how these currents transport heat and salt and fresh water. The vessel will measure the entire water column every 30 miles from Tasmania to the ice encompassing Antarctica. Some instruments are designed to be left behind for future monitoring.

Scientists will focus their measurements on the amount of carbon in the water. This will allow them to calculate the amount of carbon dioxide absorbed into the Southern Ocean.

Researchers believe the Southern Ocean absorbs more carbon dioxide than it releases. …