Ozonewatch 2018

  • Released Monday, March 18, 2019

Each year for the past few decades during the Southern Hemisphere spring, chemical reactions involving chlorine and bromine cause ozone in the southern polar region to be destroyed rapidly and severely. This depleted region is known as the “ozone hole.”

The area of the ozone hole is determined from a map of total column ozone. It is calculated from the area on the Earth that is enclosed by a line with a constant value of 220 Dobson Units (a unit of measure for total ozone.) The value of 220 Dobson Units is chosen since total ozone values of less than 220 Dobson Units were not found in the historic observations over Antarctica prior to 1979. Also, from direct measurements over Antarctica, a column ozone level of less than 220 Dobson Units is a result of the ozone loss from chlorine and bromine compounds.

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Credits

Please give credit for this item to:
NASA's Goddard Space Flight Center

Release date

This page was originally published on Monday, March 18, 2019.
This page was last updated on Wednesday, November 15, 2023 at 12:40 AM EST.