Australian Rainfall and Surface Temperature Variations Associated with the
Southern Hemisphere Annular Mode
Harry H. Hendon, David W. J. Thompson, and Matthew C. Wheeler
2007: J. Climate, 20, 2452-2467.
Abstract
Daily variations in Australian rainfall and surface temperature associated with the
Southern Hemisphere Annular Mode (SAM) are documented using observations for the
period 1979-2005. The high index polarity of the SAM is characterized by a poleward
contraction of the midlatitude westerlies. During winter, the high index polarity of the
SAM is associated with decreased daily rainfall over southeast and southwest Australia,
but during summer it is associated with increased daily rainfall on the southern east coast
of Australia and decreased rainfall in western Tasmania. Variations in the SAM explain
up to ~15% of the weekly rainfall variance in these regions, which is comparable to the
variance accounted for by the El Nino/Southern Oscillation, especially during winter. The
most widespread temperature anomalies associated with the SAM occur during the spring
and summer seasons, when the high index polarity of the SAM is associated with
anomalously low maximum temperature over most of central/eastern subtropical
Australia. The regions of decreased maximum temperature are also associated with
increased rainfall. Implications for recent trends in Australian rainfall and temperature are
discussed.