Morioka Y. auteur aut IRD Tozuka T. auteur aut IRD Masson S. auteur aut IRD Terray Pascal auteur aut IRD Luo J. J. auteur aut IRD Yamagata T. auteur aut IRD text journalArticle eng text/pdf born digital access The growth and decay mechanisms of subtropical dipole modes in the southern Indian and South Atlantic Oceans and their impacts on southern African rainfall are investigated using results from a coupled general circulation model originally developed for predicting tropical climate variations. The second (most) dominant mode of interannual sea surface temperature (SST) variations in the southern Indian (South Atlantic) Ocean represents a northeast-southwest oriented dipole, now called subtropical dipole mode. The positive (negative) SST interannual anomaly pole starts to grow in austral spring and reaches its peak in February. In austral late spring, the suppressed (enhanced) latent heat flux loss associated with the variations in the subtropical high causes a thinner (thicker) than normal mixed layer thickness that, in turn, enhances (reduces) the warming of the mixed layer by the climatological shortwave radiation. The positive (negative) pole gradually decays in austral fall because the mixed layer cooling by the entrainment is enhanced (reduced), mostly owing to the larger (smaller) temperature difference between the mixed layer and the entrained water. The increased (decreased) latent heat loss due to the warmer (colder) SST also contributes to the decay of the positive (negative) pole. Although further verification using longer observational data is required, the present coupled model suggests that the South Atlantic subtropical dipole may play a more important role in rainfall variations over the southern African region than the Indian Ocean subtropical dipole. specialized 032 020 25 12 4029-4047 2012 0894-8755 https://www.documentation.ird.fr/hor/fdi:010057045 10.1175/jcli-d-11-00396.1 0894-8755 [F B010057045] https://www.documentation.ird.fr/hor/fdi:010057045 https://www.documentation.ird.fr/intranet/publi/2012/08/010057045.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2012-09-03 2017-08-23 fdi:010057045 fre