The Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite acquired data for this map of ozone concentrations over Antarctica on September 12, 2010.
This series of images shows the Antarctic ozone hole on the day of its maximum depletion in 1979, 1987, 2006, and 2010; that is, the days with the thinnest ozone layer.
NASA satellites have observed the Antarctic ozone hole since the late 1970s—before and after nations agreed to stop producing chemicals that destroy the ozone layer.
In 1979, Antarctic ozone levels dropped below 200 Dobson Units for the first time on record. This threshold became the standard for defining the ozone hole. In 2008, minimum ozone levels dropped to 100 Dobson Units on October 4.
New research from NASA scientists shows that the amount of chlorine in the stratosphere over the South Pole is declining at the same time that ozone holes are becoming less severe.