Saturday, February 6, 2010
CONVERSION CAN BE TREACHEROUS – the Southern Ocean
We’ve been traveling since last night and all day south of Port Stanley, heading South.
Since the 50th parallel we’ve been in an area called the convergence. As I write this, we are at the 56th parallel latitude south of the equator. We are approaching the Southern Ocean that encircles Antarctica.
The conversion is the collision and merging of the Pacific, Atlantic and Indian oceans. The colder temperatures of the Antarctic waters slip below the warmer waters of the other water bodies and there is a rapid drop in water temperature. Think freezing and ski attire. We are.
This change in temperature prompts a fog and mist. It’s a blue gray haze that we’ve observed at somewhat of a distance, closer to the horizon. Mariners call this ice blink, and they take it as a sign that ice floes are nearby. We have noticed this haze becoming more prominent over time. The waters look dark blue almost purple. Soon we expect to see the first floating ice. And to hear it rattling down the side of the ship.
This zone of convergence is an ecological barrier for warmer species going south and vice versa. This is summer now.
If you think of the Antarctic as a continent as more akin to the sun, at the center of things, the waters of the Southern Ocean revolve around it in a west to east direction.
This Southern Ocean is a major conveyor belt of waters from all regions of the world.
It moves at a rate – so we’re told by our expert docents on board – of 170 million cubic yards per second.
You’ve seen how waters get caught and spin around by the contours of a shore. The Weddell sea is south east of our heading and it is where my hero, Shackleton, sailed to make his cross-continental expedition.
The circumpolar waters come into that sea and turn around in a gyre that circulates and delivers the needed nutrients for Antarctic life.
In the winter this area we are sailing through now is covered in ice at a depth of 3 meters or about 9 feet. In the winter, if we could be at this same location, we’d see ice in all directions. And that’s why we’re here now – in the summer.
There are great and beautiful books to read about this part of the world. David Campbell wrote a book called the Crystal Desert, Summers in Antarctica. It is gorgeously written. He describes the Southern Ocean as “a manic sea” because “between the tempests there is tranquility and light.” We are headed toward the South Shetland Islands, a chain of Islands including Elephant Island where Shackleton’s men were marooned while Shackleton went for help. According to Campbell, “the distance between cyclones is measured in time, three to five days apart.” So you have a taste of what that means, Campbell wrote, “The cyclonic winds march around the compass, so at one moment they will heard the icebergs against the shore in a groaning cluster, and a few hours later waft them out to see like feathers on a pond.”
I wouldn’t recommend another book if it wasn’t also terrific. Stephen J, Pyne wrote a book, The Ice, years ago and it is poetic and marvelous for its word sketches of this amazing area of the world. On this subject, Pyne says, “storm cells swirl over the ocean, epicycles of the polar vortex; sea ice floes, like a belt of asteroids, circle endlessly, a life cycle of freezing and melting; ice bergs, large and small, circle like comets around their peculiar icy sun.”