Testing our understanding of Arctic denitrification using MIPAS-E satellite measurements in winter 2002/2003 S. Davies1, G. W. Mann1, K. S. Carslaw1, M. P. Chipperfield1, J. J. Remedios2, G. Allen3, A. M. Waterfall4, R. Spang5, and G. C. Toon6 1Institute for Atmospheric Science, School of Earth and Environment, University of Leeds, UK 2Earth Observation Science, Space Research Centre, University of Leicester, UK 3School of Earth, Atmospheric and Atmospheric Sciences, University of Manchester, UK 4Rutherford Appleton Laboratory, Chilton, Didcot, UK 5Institut 1: Stratosphare: Forschungszentrum Juelich, 52 425, Juelich, Germany 6Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Abstract. Observations of gas-phase HNO3 and N2O
in the polar stratosphere from the Michelson
Interferometer for Passive Atmospheric Sounding aboard the ENVISAT
satellite (MIPAS-E) were made during the cold Arctic winter of 2002/2003.
Vortex temperatures were unusually low in early winter and remained
favourable for polar stratospheric cloud formation and denitrification
MIPAS-E observations provide the first dataset with
sufficient coverage of the polar vortex in mid-winter
which enables a reasonable estimate of the
timing of onset and spatial distribution of denitrification of the Arctic
lower stratosphere to be performed.
We use the observations from MIPAS-E to test the evolution of denitrification
in the DLAPSE (Denitrification by Lagrangian Particle Sedimentation)
microphysical denitrification model coupled to the SLIMCAT chemical
transport model. In addition, the predicted denitrification from a simple
equilibrium nitric acid trihydrate-based scheme is also compared with
Modelled denitrification is compared with in-vortex NOy
observations from the balloon-borne MarkIV interferometer in mid-December.
Denitrification was clearly observed by MIPAS-E in mid-December 2002 and
reached 80% in the core of the vortex by early January 2003.
The DLAPSE model is broadly
able to capture both the timing of onset and the spatial distribution of
the observed denitrification. A simple thermodynamic
equilibrium scheme is able to reproduce the observed denitrification
in the core of the vortex but overestimates denitrification closer to the
vortex edge. This study also suggests that the onset of denitrification in
simple thermodynamic schemes may be earlier than in the MIPAS-E observations.
Citation: Davies, S., Mann, G. W., Carslaw, K. S., Chipperfield, M. P., Remedios, J. J., Allen, G., Waterfall, A. M., Spang, R., and Toon, G. C.: Testing our understanding of Arctic denitrification using MIPAS-E satellite measurements in winter 2002/2003, Atmos. Chem. Phys., 6, 3149-3161, doi:10.5194/acp-6-3149-2006, 2006.