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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, D18106, doi:10.1029/2005JD005860, 2005

Meridional circulation and the surface pressure change associated with the Southern Annular Mode: Comparison with the Arctic Oscillation

Yuhji Kuroda

Meteorological Research Institute, Tsukuba, Japan


Abstract

Eddy forced meridional circulation and corresponding surface pressure change associated with the month-to-month variability of the Southern Annular Mode (SAM) are examined in the framework of the Eulerian mean dynamics, and they are compared with those of the Arctic Oscillation (AO). Effect of wave forcings on the surface pressure was diagnosed by means of a zonal mean quasi-geostrophic model on the sphere. It is found that the surface pressure change associated with the SAM is mainly produced by the meridional circulation driven by mechanical and thermal eddy forcings of zonal wave number 1 and mechanical forcing by high-frequency transient eddies. This contrasts with the surface pressure change associated with the AO, which is produced by the mechanical forcing by zonal wave number 2 or 3 and high-frequency transient eddies. Close relationship between the meridional circulation and surface pressure was found not only for the month-to-month variability but also for the decadal variability as also observed for the AO.

Received 9 February 2005; accepted 13 June 2005; published 30 September 2005.

Keywords: Southern Annular Mode; meridional circulation; surface pressure change.

Index Terms: 3309 Atmospheric Processes: Climatology (1616, 1620, 3305, 4215, 8408); 3362 Atmospheric Processes: Stratosphere/troposphere interactions; 1620 Global Change: Climate dynamics (0429, 3309).

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Citation: Kuroda, Y. (2005), Meridional circulation and the surface pressure change associated with the Southern Annular Mode: Comparison with the Arctic Oscillation, J. Geophys. Res., 110, D18106, doi:10.1029/2005JD005860.