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Ann. Geophys., 21, 805-817, 2003
www.ann-geophys.net/21/805/2003/
© European Geosciences Union 2003
Classification of hemispheric monthly mean stratospheric potential vorticity fields
R. Huth1 and P. O. Canziani2,3
1Institute of Atmospheric Physics, Praha, Czech Republic
2Grupo de Atmósfera Media, Departamento de Ciencias de la Atmósfera y los Océanos, Facultad de Ciencias Exactas y Naturales, CONICET/Universidad de Buenos Aires, Buenos Aires, Argentina
3Unidad Docente Ciencias Básicas Matemática, Facultad Regional Buenos Aires, Universidad Tecnológica Nacional, Argentina
Abstract. Monthly mean NCEP
reanalysis potential vorticity fields at the 650 K isentropic level over the
Northern and Southern Hemispheres between 1979 and 1997 were studied using
multivariate analysis tools. Principal component analysis in the T-mode was
applied to demonstrate the validity of such statistical techniques for the
study of stratospheric dynamics and climatology. The method, complementarily
applied to both the raw and anomaly fields, was useful in determining and
classifying the characteristics of winter and summer PV fields on both
hemispheres, in particular, the well-known differences in the behaviour and
persistence of the polar vortices. It was possible to identify such features as
sudden warming events in the Northern Hemisphere and final warming dates in
both hemispheres. The stratospheric impact of other atmospheric processes, such
as volcanic eruptions, also identified though the results, must be viewed at
this stage as tentative. An interesting change in behaviour around 1990 was
detected over both hemispheres.
Key words. Meteorology and
atmospheric dynamics (middle atmosphere dynamics; general circulation;
climatology)
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