At the bottom of the world, fifty people are looking forward to seeing the sun peek above the horizon on or around September 22 – the first time they have seen the sun in six months. NOAA ESRL/ GMD personnel LTJG Heather Moe and Johan Booth spent the Antarctic winter working at NOAA’s Atmospheric Research Observatory located at the geographic South Pole. The Amundsen-Scott South Pole Station, one of three United States research stations in Antarctica, only experiences one sunrise and sunset per year due to its location at 90˚S latitude. Although the sun officially sets on March 23 and rises on September 22, the actual sunrise and set times vary due to refraction of light on the horizon from atmospheric conditions: the sun typically rises and dips below the horizon several times before fully setting or rising. The station is completely isolated during the winter months because frigid temperatures make it impossible for aircraft to land. This past winter South Pole was especially cold: the crew experienced a low temperature of -105.5⁰ F (-76.2⁰ C) in July and spent several other days below -100⁰ F. To view the South Pole sunrise, please go the live NOAA/ESRL web camera at:

http://www.esrl.noaa.gov/obop/spo/livecamera.html

Sunrise over the Antarctic continent also signifies the onset of the yearly ozone hole formation. NOAA staff at the South Pole launches ozonesonde instruments on large balloons to ascertain the vertical profile of ozone in the Antarctic stratosphere. As the balloon carrying the instrument ascends through the atmosphere, the ozonesonde collects information about ozone and standard meteorological quantities such as pressure, temperature and humidity. The balloon can typically ascend to altitudes of about 115,000 feet (35 km) before it bursts. Polar ozonesonde profiles provide a detailed vertical measurement of ozone that can be made during dark periods when satellite ozone observations are limited due to the lack of sunlight over Antarctica during the austral winter. Antarctic ozone depletion occurs primarily between the altitudes of 12 and 20 kilometers, a region where polar stratospheric clouds, necessary for the chlorine-catalyzed chemical ozone destruction process, readily form. Progress of the 2012 ozone hole can be followed at the website:

http://esrl.noaa.gov/gmd/dv/spo_oz/

Background: A wide range of baseline atmospheric measurements have been acquired at South Pole by NOAA/ESRL and its predecessor organizations since the International Geophysical Year (IGY), 1957. South Pole’s atmospheric carbon dioxide greenhouse gas record pre-dates the better-known Mauna Loa carbon dioxide curve by one year, making it the longest carbon dioxide sampling record on earth. In addition to monitoring greenhouse gases, the winter crew also measures atmospheric particulates, solar radiation, and ozone-depleting gases. Each year NOAA releases over 40 ozonesondes on high-altitude balloons to study the stratospheric ozone layer and to document the onset and severity of the annual Antarctic “Ozone Hole”; the continuous NOAA ozonesonde record dates back to 1986.
Significance: Continuous long term records of atmospheric parameters measured at the South Pole, where the mantra is “the cleanest air on earth”, have documented a wide range of changes in the composition, chemistry, and radiative balance of the atmosphere over the Antarctic continent since the inception of the measurements in 1957. Many of these changes are related to mankind’s combustion of fossil fuels and from the release of industrial and household chemicals into the atmosphere.
http://www.esrl.noaa.gov/dv/spo_oz/movies/index.html

Contact information
Name: Brian Vasel
Tel: (303) 497-6823
Brian.Vasel@noaa.gov