Ozone Hole:

The ozone hole is a thinning of the ozone layer or loss of stratospheric ozone over Antarctica. The area of the ozone hole is defined as the size of the region with total ozone amounts below 220 Dobson Units (DU), a unit of measurement that refers to the thickness of the ozone layer from the surface to the top of the atmosphere, also known as total column ozone amount. Prior to 1979, total column ozone values over Antarctica never fell below 220 DU. Direct measurements over Antarctica have proven that the ozone hole over the past few decades is the result of human activities--the release of huge quantities of chlorofluorocarbons (e.g. chlorine, fluorine, Freon) and other ozone depleting substances into the atmosphere. During the Southern Hemisphere spring, around September-October, chemical reactions involving manufactured chemicals cause ozone on the southern polar region to be rapidly destroyed.

October, 2014 ozone hole annual maximum:

ozone hole

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NASA has been monitoring the ozone layer and the ozone hole through satellite observations since the 1970's, beginning with the Nimbus satellites through the Aura satellite (2004-present)

References:

A Story of Ozone: Earth's Natural Sunscreen

NASA Earth Observatory World of Change: Antarctic Ozone Hole

NASA GSFC Multimedia: Exploring Ozone

NASA | Big Ozone Holes headed For Extinction By 2040

Ozone Hole to Remain Large During Cold Years

Satellite Information:

NASA Aura's Ozone Monitoring Instrument (OMI)

NASA Aura Mission: Ozone

NASA Ozone Hole Watch

Contact Us:

ses@essic.umd.edu