ANTARCTIC STRATOSPHERIC WARMING REVIEWED IN LIGHT OF 1967 OBSERVATIONS

Unlike the Northern Hemisphere where a number of extremely well documented case studies to very high levels facilitate the study of polar stratospheric warming, most investigations so far in the Southern Hemisphere have been directed mainly to the 100 mb, or occasionally 50 mb level. In 1967 it was possible to draw a series of daily 30 mb contour charts through the spring period, and 30 mb isotherm charts for the month of October over the Antarctic. The contour charts showed that the polar vortex: changed little in depth until the end of September then filled steadily; was initially single centred, became double‐centred, then finally single centred again; developed a double‐wave pattern, the perturbations moving progressively and regularly around the vortex. The movement of these waves was accompanied by short period, but marked, temperature changes at a given point (warm ridges and cold troughs), but even after the major warming was completed at this level over the continent, the circulation was still predominantly cyclonic. From the limited information available it appears that in 1967 the short period temperature changes may have been more pronounced than in some earlier years, but the general warming trend was normal. Wave movement around the polar vortex could also be detected in an autumn and winter season, and apparent mid‐winter stratospheric warmings previously reported or observed may be ascribed to the passage of migratory warm ridges, although this explanation is not advanced for the mid‐winter warming event inferred over McMurdo in 1963. Copyright © 1969 Royal Meteorological Society