Analysis using NOAA satellite data indicates that at 20.8 million square kilometers (about 8 million square miles)*, the ozone hole over the South Pole reached its maximum annual size on September 22, 2013. Shown here is the total ozone concentration over the South Pole on September 22, 2013 using data from NOAA’s Total Ozone Analysis using SBUV/2 and TOVS measurements. The “hole” is designated as the area where the total ozone concentration is below 220 Dobson units (a measure of thickness). In this image, those values are colored red.
Science teams from NOAA, NASA, and the World Meteorological Organization have been monitoring the ozone layer from the ground and with a variety of instruments on satellites and balloons since the 1970s. These ozone instruments capture different aspects of ozone depletion. The independent analyses ensure that the international community understands the trends in this critical part of Earth's atmosphere. The resulting views of the ozone hole have slight differences in the computation of the size of the ozone hole, its depth, and record dates.
*The original post of this image on October 21, 2013 has been modified to reflect more complete analyses by the respective agencies.