Atmos. Chem. Phys., 14, 3231-3246, 2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Arctic stratospheric dehydration – Part 2: Microphysical modeling
I. Engel1,*, B. P. Luo1, S. M. Khaykin2,3, F. G. Wienhold1, H. Vömel4, R. Kivi5, C. R. Hoyle6,7, J.-U. Grooß8, M. C. Pitts9, and T. Peter1
1Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
2Central Aerological Observatory, Dolgoprudny, Moscow Region, Russia
3LATMOS-IPSL, Université Versailles St. Quentin, CNRS/INSU, Guyancourt, France
4Deutscher Wetterdienst, Meteorological Observatory Lindenberg – Richard Aßmann Observatory, Lindenberg, Germany
5Finnish Meteorological Institute, Arctic Research, Sodankylä, Finland
6Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
7Swiss Federal Institute for Forest Snow and Landscape Research (WSL) – Institute for Snow and Avalanche Research (SLF), Davos, Switzerland
8Institut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Jülich, Germany
9NASA Langley Research Center, Hampton, Virginia, USA
*now at: Institut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Jülich, Germany

Abstract. Large areas of synoptic-scale ice PSCs (polar stratospheric clouds) distinguished the Arctic winter 2009/2010 from other years and revealed unprecedented evidence of water redistribution in the stratosphere. A unique snapshot of water vapor repartitioning into ice particles was obtained under extremely cold Arctic conditions with temperatures around 183 K. Balloon-borne, aircraft and satellite-based measurements suggest that synoptic-scale ice PSCs and concurrent reductions and enhancements in water vapor are tightly linked with the observed de- and rehydration signatures, respectively. In a companion paper (Part 1), water vapor and aerosol backscatter measurements from the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) and LAPBIAT-II (Lapland Atmosphere–Biosphere Facility) field campaigns have been analyzed in detail. This paper uses a column version of the Zurich Optical and Microphysical box Model (ZOMM) including newly developed NAT (nitric acid trihydrate) and ice nucleation parameterizations. Particle sedimentation is calculated in order to simulate the vertical redistribution of chemical species such as water and nitric acid. Despite limitations given by wind shear and uncertainties in the initial water vapor profile, the column modeling unequivocally shows that (1) accounting for small-scale temperature fluctuations along the trajectories is essential in order to reach agreement between simulated optical cloud properties and observations, and (2) the use of recently developed heterogeneous ice nucleation parameterizations allows the reproduction of the observed signatures of de- and rehydration. Conversely, the vertical redistribution of water measured cannot be explained in terms of homogeneous nucleation of ice clouds, whose particle radii remain too small to cause significant dehydration.

Citation: Engel, I., Luo, B. P., Khaykin, S. M., Wienhold, F. G., Vömel, H., Kivi, R., Hoyle, C. R., Grooß, J.-U., Pitts, M. C., and Peter, T.: Arctic stratospheric dehydration – Part 2: Microphysical modeling, Atmos. Chem. Phys., 14, 3231-3246, doi:10.5194/acp-14-3231-2014, 2014.
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