Tracer structures in the southern hemispheric middle stratosphere observed by CRISTA-1 Original Research Article

We present observations of N2O in the southern hemispheric stratosphere (10 mbar) made by the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) instrument during its first mission in early November 1994. The observations took place about three weeks after a strong interaction of the South polar vortex with the subtropical transport barrier, which led to considerable transport of tropical air towards higher latitudes. The remnants of this transport formed a coherent structure of subtropical air that persisted until the observation period of CRISTA. The formation of this tracer structure is discussed by means of meteorological field obtained from analyses of the Met Office (UKMO) and by idealized tracer transport studies.