Role of the Stratospheric Polar Freezing Belt in Denitrification
A. Tabazadeh,1*
E. J. Jensen,1
O.
B. Toon,2
K. Drdla,1
M. R. Schoeberl3
Homogeneous freezing of nitric acid hydrate particles can produce a
polar freezing belt in either hemisphere that can cause denitrification. Computed denitrification profiles for one Antarctic and two Arctic cold winters are presented. The vertical range over
which denitrification occurs is normally quite deep in the Antarctic
but limited in the Arctic. A 4 kelvin decrease in the temperature of
the Arctic stratosphere due to anthropogenic and/or natural effects can
trigger the occurrence of widespread severe denitrification. Ozone loss
is amplified in a denitrified stratosphere, so the effects of falling
temperatures in promoting denitrification must be considered in
assessment studies of ozone recovery trends.
1 NASA Ames Research Center, Earth Science
Division, MS:245-4 Moffett Field, CA 94035, USA.
2 Laboratory for Atmospheric and Space Physics,
Program in Atmospheric and Oceanic Sciences, University of Colorado,
Boulder, CO 80309, USA.
3 NASA Goddard Space Flight
Center, Greenbelt, MD 20771, USA.
*
To whom correspondence should be addressed. E-mail:
atabazadeh{at}mail.arc.nasa.gov
