By Patrick Cullis, CIRES and NOAA scientist

After six straight months of darkness, the Sun has finally returned to the sky above the Amundsen-Scott South Pole Station.  NOAA scientists working at the station and collecting air samples at the Atmospheric Research Observatory (ARO) experience only one sunrise, and one sunset per year due to the unique location on Earth’s axis.  Along with the return of sunlight above the South Pole and Antarctica, so does the Ozone Hole.  The returning sunlight activates a buildup of chlorine in the stratosphere that destroys much of the protective ozone overhead.  This is the period where NOAA scientists ramp up their measurements in a government mandated mission to monitor the health of the Ozone Layer.

South Pole Plastic Balloon Launch composite – Photo Credit: Robert Schwarz

In the extremely frigid temperatures at the South Pole, sometimes reaching -100F, large plastic balloons are used to carry a small instrument measuring ozone all the way up to over 100,000 feet above sea level.  As the instrument, called an ozonesonde, rises up through the atmosphere it passes through the decimated ozone layer and transmits measurement data back to a ground station.  Once the data is collected during the three hour flight, it is sent back to the Global Monitoring Division headquartered in Boulder, Colorado where it is published for scientists around the world to use.