This animation created from data from the Microwave Limb Sounder
instrument on NASA's Aura spacecraft depicts the complex interaction of
chemicals involved in the destruction of ozone during the 2005 Arctic
winter. Red is high, blue/purple is low for all chemicals, and data are
taken at an altitude of about 19 kilometers (12 miles). As temperatures
dip, nitric acid levels drop, indicating the presence of polar
stratospheric clouds, which destroy ozone. Levels of hydrogen chloride
(the primary "safe" form of chlorine) are shown dropping, while levels of
chlorine monoxide (the primary "dangerous" form of chlorine that destroys
ozone) rise, and ozone is destroyed (ozone levels generally go down after
about January 20).
The animation also illustrates how air motions change ozone levels. Prior
to about January 20, ozone levels increase as ozone is transported down
from higher altitudes. After that, ozone decreases gradually, and appears
to move around on the surface as horizontal air motions change the shape
of the polar vortex and move air into and out of it. Since the highest
ozone is mostly around the edge of the vortex, this can increase the
ozone inside it.
