Antarctica

Week 3 December 17 2006 Where is the South Pole and What's it Like?

Accompanying Photos

I thought I should make sure everyone knows where the South Pole is. Often the whole of Antarctica is referred to as the South Pole. However, when I say I'm at the South Pole, I mean the South Pole. It is the bottom of the world, the axis around which the earth spins.

The most striking thing about the South Pole is that in the summer the sun never sets. In a single day it never gets noticeably higher or lower in the sky. It goes around the sky once a day at the same hight above the horizon. Over a 6 month period the sun goes from the horizon at sunrise, slowly spirals up to it's highest point in mid summer, and then slowly spirals down to the horizon for a sunset 6 months later. The South Pole has one day and one night each year. This is due to the earth going around the sun once a year, the tilt of the axis of the earth to the orbit around the sun, and the fact the earths spins on it's axis once a day.

At sunset and sunrise the sun slowly skims the horizon gradually vanishing over a few days, or reappearing. Of course with the sun just below the horizon it doesn't immediately become dark, and there are a few weeks of twilight either side of the winter night. In all its about four and half months of total darkness during the South Pole winter night. Even then when the moon is out, with moonlight reflecting off the white snow surface, it can be bright enough to see colours outside. The colours of the sky at sunset can be amazing with bright deep oranges, and if you're lucky a green flash as the sun finally disappears. After sunset the plateau turns a steely grey and the shadow of the earth slowly rises in the sky until there is only a glow where the sun is below the horizon. Stars start to appear and the Southern Cross takes shape high above, and the impressive Scorpio dominates the constellations, while Orion skims the horizon upside down with his head just out of sight. It's an amazing sight and all you have to do to see it is to commit to staying at the South Pole for a year.

The moon is also interesting. It's not as obvious during the summer when it's difficult to see, but the moon is above the horizon for 2 weeks, and then below for 2 weeks. This is due to the moon taking 4 weeks to orbit the earth, and the fact that the orbit of the moon is not in the same plane as the equator of the earth. So for half it's orbit around the earth it can be seen at the South Pole, and then it goes below the horizon for the other half. While it is up it also goes around the horizon once a day like the sun. The stars on the other hand never set. All year round the same stars are circling overhead in the sky. You just can't see them in the summer.

Most of Antarctica is a high plateau of ice and snow. While South Pole is not in the exact center, it is well inland of what is known as East Antarctica. South Pole is on an ice sheet, which is moving towards the coast of Antarctica, where the flow of ice forms more well defined streams, called glaciers. The ice sheet at South Pole is about 3000 meters deep, and is moving at about 10 meters a year. An unusual result of this is that the marker which locates the South Pole needs updating each year as the ice moves the marker away by 10 meters each year. This means the patch of ice that Amundsen's and Scott's teams reached 95 years ago is almost 1km from the present South Pole marker.

At some point it was decided to have two South Pole markers. There is the Geographic South Pole, with a sign and an American flag, and a Pole marker locating the South Pole, and then there is the Ceremonial Pole. My understanding is that when the Geographic South Pole was much further away from the station than now a more elaborate South Pole was set up close to the station so that visitors didn't have to make the trek to the real South Pole, . The ceremonial South Pole is a reflecting sphere on a thick bamboo pole, painted red and white like a barbers pole. It is surrounded by the flags of the original signature nations of the Antarctic Treaty. These days the Geographic South Pole is very close to the station, and the ceremonial Pole has been moving around a bit. They are now located very close together. I personally feel the 2 pole system should be done away with, and the treaty nation flags should be flown around the Geographic South Pole.

Another thing about South Pole is that it is cold. The highest recorded temperature for Pole is -13.6°C / +7.5°F, while the lowest is -82.8°C / -117.0°F, with an average of -49.5°C / -57.1°F. The coldest I've experienced was -106.0°F in the winter of 2000. That's fairly cold. There are a number of reasons Antarctica is so cold. As you go above sea level it gets colder. So the altitude contributes. Also because almost all of Antarctica is covered in bright white snow and it reflects most of the sun's warming radiation. Finally the sun never gets very high above the horizon (23.5° at Pole), and the strength of the sunlight over a given area is much less than somewhere like the equator, where the sun can be directly overhead. It is also interesting that that South Pole is much colder than the North Pole. The reason for this is that the North Pole is an ocean which freezes over in the winter. The water, which is obviously not below freezing moderates the temperature, and it is not at altitude.

Antarctica has a reputation for fierce winds. This is very true at the coast. At the coast the plateau drops down to sea level very steeply. The cold dense air over the plateau rapidly falls under the influence of gravity producing these fierce winds at the coast. Winds produced this way are called katabatic winds. However on the plateau, such as at South Pole, the topography is quite flat and the wind does not gain as much energy as it does at the coast. While there is fairly constant katabatic breeze at the Pole, which is almost always from the same direction, it never gets very windy. The strongest recorded wind at Pole was 48 knots, and the average is 10.7 knots. Not very strong.

As I've mentioned most of Antarctica is a high plateau. South Pole is at an altitude of 9300 feet above sea level. However the atmosphere at the Poles is thinner than at the equator. This makes the atmospheric pressure lower than at the same altitude at the equator. The difference is significant, and it has a noticeable effect on how we react to the altitude, especially when we first arrive. To make this quantitative, they report something called the physiological altitude, which is the altitude we would be at if we were at the equator for the same atmospheric pressure. For instance the physiological altitude right now is 10625 feet. This altitude is just above the point where altitude sickness can be a problem. This year a number of people have suffered serious altitude sickness soon after arrival and had to be medivaced back to McMurdo.

With so much snow and ice here you might think it snows a lot. It actually hardly ever snows, and then the snow is not like the snow most people are used to. Most of the time it is fine ice crystals which often fall when there is a blue sky. Very cold air has a very low capacity to carry water. Even though the air is very dry, because it can carry very little moisture, for the same reason it can easily become super saturated which is when the ice crystals form in the air. Every so often when it is warmer it snows as small ice pellets. With it being so dry and cold the snow on the surface has a strange texture. It's more like dry sand and makes an unusual crunching sound when you walk on it. It also makes skiing difficult as the thin water layer that normally forms under skis, which gives the nice glide, doesn't form here. Imagine skiing on firm dry sand.

The big news for IceCube this week was the completion of the first string installation for the season. In the AMANDA days a hole took days to drill. The problem with this, apart from the time, was that it took lots of fuel. The faster you drill the hole, the less energy is lost to the surrounding ice. The AMANDA drill used multiple pieces of hose that had to be joined as the hole got deeper. IceCube uses one huge hose and more energy to drill faster. The problem with that is that the IceCube drill is much more complex, with automatic computer controls, and lots of sensors watching the performance. Of course the more complex you make something the more often is breaks down. This hole was no exception with numerous problems. But the hope is that most are now ironed out and drilling will speed up.

In my world we continued to install computer equipment. We have racks in place and powered. By the end of the week we had almost all the equipment in the racks and about 75% cabled internal to the rack. Inter rack cabling is going to be a problem because all our custom made cables are now the wrong length after they had to be rearranged to give code compliant egress paths. Have I already wondered out loud why no one looked at the drawings and maybe mentioned something before we arrived at Pole. We'll deal with that this week. We also reached the point where ESD (Electro Static Discharge) protection became important. So we are now decked out in smart anti ESD lab coats while working in the ICL.

Finally I had an exciting visit by Flat Shark, world-class explorer, representing the fifth grade class at Lillian Schumacher Elementary School, Liberty, Missouri. We took some hero shots at the South Pole, had dinner in the galley, and he helped me with my work. Maybe he'll visit Australia next.

To be continued....

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