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View the latest status of the ozone layer over the Antarctic,
with a focus on the ozone hole. Satellite instruments monitor
the ozone layer, and we use their data to create the images
that depict the amount of ozone.
Click any map image to bring up a new page with a
high-resolution image.
Ozone Movies
Watch a movie of the daily progression through a season or
the annual progression of the means for a month. A table
of all ozone movies are available in our
multimedia
section.
Ozone facts
What is ozone?
Ozone is a colorless gas. Chemically, ozone is very active;
it reacts readily with a great many other substances. Near
the Earth’s surface, those reactions cause rubber to crack,
hurt plant life, and damage people’s lung tissues. But
ozone also absorbs harmful components of sunlight, known as
“ultraviolet B”, or “UV-B”. High
above the surface, above even the weather systems, a tenuous
layer of ozone gas absorbs UV-B, protecting living things
below.
What is a Dobson Unit?
The Dobson Unit (DU) is the unit of measure for total ozone.
If you were to take all the ozone in a column of air
stretching from the surface of the earth to space, and bring
all that ozone to standard temperature (0 °Celsius) and
pressure (1013.25 millibars, or one atmosphere, or
“atm”), the column would be about 0.3
centimeters thick. Thus, the total ozone would be 0.3
atm-cm. To make the units easier to work with, the
“Dobson Unit” is defined to be 0.001 atm-cm. Our
0.3 atm-cm would be 300 DU.
What is the ozone hole?
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. 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.