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Ann. Geophys., 25, 1279-1298, 2007
www.ann-geophys.net/25/1279/2007/
© European Geosciences Union 2007
Polar vortex evolution during Northern Hemispheric winter 2004/05
T. Chshyolkova1, A. H. Manson1, C. E. Meek1, T. Aso2, S. K. Avery3, C. M. Hall4, W. Hocking5, K. Igarashi6, C. Jacobi7, N. Makarov8, N. Mitchell9, Y. Murayama6, W. Singer10, D. Thorsen11, and M. Tsutsumi2
1Institute of Space and Atmospheric Studies, University of Saskatchewan, 116 Science Place, Saskatoon, SK, S7N 5E2, Canada
2National Institute of Polar Research, Tokyo, Japan
3CIRES, University of Colorado, Boulder, USA
4Tromsø Geophysical Observatory, University of Tromsø, Tromsø, Norway
5Department of Physics and Astronomy, University of Western Ontario, London, Canada
6National Institute of Information and Communications Technology, Tokyo, Japan
7Institute for Meteorology, University of Leipzig, Leipzig, Germany
8Institute for Experimental Meteorology, SPA "Typhoon", Obninsk, Russia
9Centre for Space, Atmospheric, and Oceanic Sciences, Department of Electronic and Electrical Engineering, University of Bath, Bath, UK
10Leibniz-Institut fur Atmospharen physik an der Universitat Rostock, Kühlungsborn, Germany
11Department of Electrical and Computer Engineering, University of Alaska, Fairbanks, USA
Abstract. As a part of the project "Atmospheric Wave Influences upon the Winter Polar
Vortices (0–100 km)" of the CAWSES program, data from meteor and Medium
Frequency radars at 12 locations and MetO (UK Meteorological Office) global
assimilated fields have been analyzed for the first campaign during the
Northern Hemispheric winter of 2004/05. The stratospheric state has been
described using the conventional zonal mean parameters as well as
Q-diagnostic, which allows consideration of the longitudinal variability.
The stratosphere was cold during winter of 2004/05, and the polar vortex was
relatively strong during most of the winter with relatively weak
disturbances occurring at the end of December and the end of January. For
this winter the strongest deformation with the splitting of the polar vortex
in the lower stratosphere was observed at the end of February. Here the
results show strong latitudinal and longitudinal differences that are
evident in the stratospheric and mesospheric data sets at different
stations. Eastward winds are weaker and oscillations with planetary wave
periods have smaller amplitudes at more poleward stations. Accordingly, the
occurrence, time and magnitude of the observed reversal of the zonal
mesospheric winds associated with stratospheric disturbances depend on the
local stratospheric conditions. In general, compared to previous years, the
winter of 2004/05 could be characterized by weak planetary wave activity at
stratospheric and mesospheric heights.
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