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Ann. Geophys., 24, 1511-1521, 2006
www.ann-geophys.net/24/1511/2006/
© European Geosciences Union 2006
Stratospheric water vapour in the vicinity of the Arctic polar vortex
M. Maturilli1, F. Fierli2, V. Yushkov3, A. Lukyanov3, S. Khaykin3, and A. Hauchecorne4
1Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany
2Institute for Atmospheric Sciences and Climate, CNR, Italy
3Central Aerological Observatory, Moscow, Russia
4Service D’Aéronomie du CNRS, Verrières-le-Buisson, France
Abstract. The stratospheric water vapour mixing ratio inside, outside, and at the edge
of the polar vortex has been accurately measured by the FLASH-B Lyman-Alpha
hygrometer during the LAUTLOS campaign in Sodankylä, Finland, in January
and February 2004. The retrieved H2O profiles reveal a detailed view on
the Arctic lower stratospheric water vapour distribution, and provide a
valuable dataset for the validation of model and satellite data. Analysing
the measurements with the semi-lagrangian advection model MIMOSA, water
vapour profiles typical for the polar vortex' interior and exterior have
been identified, and laminae in the observed profiles have been correlated
to filamentary structures in the potential vorticity field. Applying the
validated MIMOSA transport scheme to specific humidity fields from
operational ECMWF analyses, large discrepancies from the observed profiles
arise. Although MIMOSA is able to reproduce weak water vapour filaments and
improves the shape of the profiles compared to operational ECMWF analyses,
both models reveal a dry bias of about 1 ppmv in the lower stratosphere
above 400 K, accounting for a relative difference from the measurements in
the order of 20%. The large dry bias in the analysis representation of
stratospheric water vapour in the Arctic implies the need for future regular
measurements of water vapour in the polar stratosphere to allow the
validation and improvement of climate models.
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