****************************************************** AIR & ATMOSPHERE ****************************************************** ********* AURORA ********* __________ QUESTION: How often and with what intensity is aurora australis seen in Antarctica? What affects these occurrences? ANSWER from April Whitt on December 6, 1994 Aurorae are seen at "night" in Antarctica, as they are in this hemisphere. It's "pitch dark" for about two months, from mid-May to mid-July. Messages that I had from John Briggs last year indicated that the aurorae were dynamic and so bright they sometimes lit the snow like a full moon. Additional information: How often are they seen? I'd say "all night" but that's not true. Sometimes they wave across the sky for hours, sometimes they get obscured by clouds or haze. Particles from the Sun colliding with Earth's upper atmosphere energize particles there, and they glow, causing the aurora. The more active the Sun, the more auroral activity. Right now we're in a relatively "quiet" period (or the Sun is, actually). In five or six years, the Sun will be more active and the aurorae will probably be more so as well. Suggestions for other resources: The American Geophysical Union, 2000 Florida Ave, NW, Washington, D.C., 20009 publishes an extensive set of books about Antarctica, with several volumes about the sky and aurorae (these can be fairly technical works). Robert Service's poem "The Ballad of the Northern Lights" includes an interesting idea of what causes aurorae. Also, check the journals of the early explorers for their accounts. Admiral Byrd's book "Alone" describes his data-recording of aurorae during the winter he spent in his under-ice hut. __________ QUESTION: What about the aurora australis? ANSWER from Deane Rink It appears only in the Antarctic winter when there is no sunlight, so I won't get to see it. I think it is caused just as the aurora borealis is: through electromagnetic interference patterns in the upper atmosphere. It is apparently the most intense at South Pole, where many good photos of it have been taken by winter-over personnel. ********************* CLEAN AIR FACILITY ********************* __________ QUESTION: How does the Clean Air Facility work? ANSWER from Katy McNitt on February 10, 1995 The Clean Air Facility is a building which is "upwind" of the main South Pole Station. At the South Pole, the surface wind usually blows from the grid north or northeast, so we have designated a Clean Air Sector upwind of our building. This is a pie-shaped area extending out from the Clean Air Facility where nobody is allowed to go without special permission. The wind we study here carries the "cleanest air on Earth," or at least the cleanest air that's being studied! Our lab, NOAA's Climate Monitoring and Diagnostics Laboratory, is interested in anything in the atmosphere that might affect the Earth's climate. We have four observatories like the one at the South Pole, and we're helping other countries build similar sites. All of these observatories are built in places with "clean air." If we can figure out what's in the cleanest air on Earth, we can use that as a "baseline" for measuring air over more polluted areas, and we can learn more about how air gets transported all over the planet. As you can imagine, it's a big job! At the South Pole Clean Air Facility we measure trace gases, aerosols, solar and terrestrial radiation, and meteorology. Two of us maintain over thirty different projects! Some are continuously running analyzers which we calibrate and maintain. Others are sampling programs where we go outside and collect air or snow samples, which are later analyzed by scientists in the United States and Australia. The job is really fun because we do something different every day, and it's exciting to see what's going on with the ozone hole over Antarctica. We also get to work outside, so it's hard to forget we're at the South Pole. ********* OXYGEN ********* __________ QUESTION: If plants make oxygen, and there are very few trees and plants in Antarctica, is it hard to breath there? ANSWER from Katy McNitt, LTJG, NOAA, S-257 Monitoring Climate Change, Amundsen-Scott South Pole Station, on January 24, 1994: It IS hard to breathe at the South Pole, but that's because we live at high altitude. The air is pretty thin here, meaning the oxygen molecules are spaced farther apart than usual, so we have to breathe more to get enough oxygen. All of Antarctica is pretty "clean" because there aren't many sources of pollution here, but we're still measuring pollutants in the air. How can this be? Well, the Earth has a complicated network of air and ocean currents that mix air and water all over the planet. A drop of water in your body has probably been around for thousands of years, traveling around the world as liquid water, water vapor in the air, or ice! So, because there aren't any trees here at the South Pole, we start out with less oxygen. But the wind brings air -- full of oxygen and nitrogen and trace gases and aerosols -- from all over the world, and by studying this air we can understand how that air gets moved around. As far as we know, the wind that blows at the South Pole is the cleanest air on Earth, but there could be someplace cleaner where nobody is taking measurements. What do you suppose we mean by "clean air," anyway? Do you know what air is made of and why oxygen is so important?