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GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L13802, doi:10.1029/2005GL022516, 2005

Solar cycle modulation of the Southern Annular Mode

Yuhji Kuroda

Climate Research Department, Meteorological Research Institute, Tsukuba, Japan


Kunihiko Kodera

Climate Research Department, Meteorological Research Institute, Tsukuba, Japan


Abstract

The effect of the 11-year solar cycle modulation on the Southern Annular Mode (SAM) in the Southern Hemisphere is examined through analysis of observational data from 1968 to 2001. It is found that the year-to-year variability of the October–November mean SAM differs significantly according to the solar activity. In high solar activity years, the SAM signal extends to the upper stratosphere during October to December and activity in the troposphere lasts until autumn, whereas in low solar activity years, the SAM signal is confined almost inside the troposphere from October to December and it disappears by January. This situation is very similar to that observed for the modulation of the winter mean North Atlantic Oscillation in the Northern Hemisphere. A possible mechanism of solar cycle modulation of the SAM is also discussed.

Received 22 January 2005; accepted 31 May 2005; published 2 July 2005.

Index Terms: 1650 Global Change: Solar variability (7537); 3362 Atmospheric Processes: Stratosphere/troposphere interactions; 3334 Atmospheric Processes: Middle atmosphere dynamics (0341, 0342); 3305 Atmospheric Processes: Climate change and variability (1616, 1635, 3309, 4215, 4513).

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Citation: Kuroda, Y., and K. Kodera (2005), Solar cycle modulation of the Southern Annular Mode, Geophys. Res. Lett., 32, L13802, doi:10.1029/2005GL022516.