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10.5194/acpd-9-26539-2009
http://www.atmos-chem-phys-discuss.net/9/26539/2009/
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http://www.atmos-chem-phys-discuss.net/9/26539/2009/acpd-9-26539-2009.pdf
26539
26575
2009-12-10
Evaluation of stratospheric chlorine chemistry for the Arctic spring 2005 using modelled and measured OClO column densities
H. Oetjen
F. Wittrock
A. Richter
richter@iup.physik.uni-bremen.de
M. P. Chipperfield
T. Medeke
N. Sheode
B.-M. Sinnhuber
M. Sinnhuber
J. P. Burrows
University of Bremen, Institute of Environmental Physics, Bremen, Germany
University of Leeds, School of Chemistry, Leeds, UK
University of Leeds, School of Earth and Environment, Leeds, UK
Centre for Ecology and Hydrology, Wallingford, UK
Chlorine dioxide, OClO, column amounts retrieved from measurements of the
SCIAMACHY satellite instrument are presented and validated by comparison
with simultaneous ground-based DOAS observations. In addition, the
measurements are compared to model calculations taking into account the
photochemical change along the light path.
<br><br>
Although OClO does not participate directly in the destruction of ozone, its
accurate measurement as well as modelling is crucial to understand the
highly perturbed chlorine chemistry in the polar vortices. SCIAMACHY OClO
slant columns retrieved during spring 2005 have been quantitatively
validated by comparison with slant columns retrieved from measurements made
in Ny-Ålesund (79° N, 12° E), Summit (73° N, 38° W) and
Bremen (53° N, 9° E). Overall, good agreement is found.
<br><br>
OClO slant column densities modelled with a set of stacked box models and
considering the light path through the atmosphere are also included in this
comparison. The model predictions differ significantly from the measured
quantities. OClO amounts are underestimated for conditions of strong
chlorine activation and at large solar zenith angles. Sensitivity studies
for several parameters in the stacked box model have been performed and it
is inferred that using the chemistry known to date, the observed OClO cannot
be adequately reproduced within the range of uncertainties given for the
various model parameters.
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