Sunset observations of ClO in the arctic polar vortex and implications
for Cl2O2 formation and ozone loss
H. Vömel, D. Toohey
Program in Atmospheric and Oceanic Sciences, University of Colorado at
Boulder
T. Deshler, C. Kröger
Department of Atmospheric Sciences, University of Wyoming, Laramie
Abstract. Chlorine oxide (ClO) was measured in situ in the perturbed arctic
vortex from a balloon launched near Kiruna, Sweden, 67ºN, at sunset
on January 27, 2000. Between 20 and 23 km, the time-dependent behavior
of ClO agrees with the functional form for the kinetics of ClO + ClO +
M -> Cl2O2 + M. The temporal change of ClO
is described well by the integral of a rate expression that includes this
reaction and thermal decomposition of Cl2O2. The
value for the rate coefficient that best describes the observed decreases
in ClO is consistent with the upper limit of the currently recommended
value, and agrees well with the results of a recent laboratory study of
ClO recombination at 190-195 K. These results reinforce the link between
man-made chlorine compounds and ozone losses in the polar regions.
Geophysical Res Ltrs. 2001GL013413
Vol. 28, pp. 4183-4186, 2001.
© 2001 AGU