Dynamics of Atmospheres and Oceans 39 (2005) 87–101 Indian Ocean Dipole mode events and austral surface air temperature anomalies N.H. Saji a, ∗ , T. Ambrizzi b , S.E.T. Ferraz b a International Pacific Research Center, 2525 Correa Road, University of Hawaii, Honolulu, HI 96822, USA b University of Sao Paulo, Brazil Received 24 December 2003; accepted 5 October 2004 Available online 16 January 2005 Abstract The impact of Indian Ocean Dipole (IOD) mode events on austral surface air temperature (SAT) variability was studied both by statistical analysis of observed/assimilated data and experiments with a mechanistic baroclinic atmospheric model. During the period of analysis (January 1958–December 1999), IOD events had the strongest im- pact on SAT anomalies during austral spring and hence, the analysis was focussed on this season. IOD events induced large scale, intercontinental correlations of SAT anomalies amongst Australia, Africa and South America. Surface temperature consistently rose (fell) abnormally and coherently in the subtropical regions of these continents during positive (negative) IOD events. Variability during non-IOD years was considerably weaker than during IOD years over these regions. Analysis of stream function anomalies at the 200 hPa level (source: NCEP/NCAR reanalysis) revealed a Rossby-wave train extending from the eastern Indian Ocean into the subtropical regions of the Pacific and Atlantic oceans. Further, the diagnosed Rossby-wave activity flux emanated from the eastern Indian Ocean and propagated along the subtropical and subpolar jet streams qualitatively in agreement with linear wave dynamics. Experiments with idealized forcing in a primitive equation mechanistic atmospheric model suggested that tropical convective anomalies in the Indian Ocean during IOD events likely affects the austral subtropics through stationary Rossby-wave propagation. © 2004 Elsevier B.V. All rights reserved. Keywords: Dipole mode index; Teleconnection; Sea surface temperature; Partial correlation; Baroclinic atmo- spheric model ∗ Corresponding author. Tel.: +1 808 956 9534; fax: +1 808 956 9425. E-mail address: saji@hawaii.edu (N.H. Saji). URL: http://iprc.soest.hawaii.edu/∼saji. 0377-0265/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.dynatmoce.2004.10.015