Upper Atmospheric Sodium and Stratospheric Warmings

H. N. Rundle Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon

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H. M. Sullivan Dept. of Physics, University of Victoria, Victoria, British Columbia

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Abstract

Time-series analysis has been used to compare twilight sodium abundances at Saskatoon and Victoria with 30-mb temperatures at several Canadian stations. Saskatoon sodium abundance variations show a high coherence with the occurrence of stratospheric warmings. The times of occurrence of the warmings and the corresponding effects in the vicinity of 90 km were found and interpreted in terms of a frontal motion. The relatively low coherence between Victoria sodium abundances and arctic stratospheric temperatures suggests that the arctic winter circulation regime does not extend to this location, at 90-km heights. Stratospheric warmings do not appear to be solely responsible for the variations in sodium abundance at Saskatoon and at Victoria.

Abstract

Time-series analysis has been used to compare twilight sodium abundances at Saskatoon and Victoria with 30-mb temperatures at several Canadian stations. Saskatoon sodium abundance variations show a high coherence with the occurrence of stratospheric warmings. The times of occurrence of the warmings and the corresponding effects in the vicinity of 90 km were found and interpreted in terms of a frontal motion. The relatively low coherence between Victoria sodium abundances and arctic stratospheric temperatures suggests that the arctic winter circulation regime does not extend to this location, at 90-km heights. Stratospheric warmings do not appear to be solely responsible for the variations in sodium abundance at Saskatoon and at Victoria.

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