Role of Local Air-Sea Interaction in Tropical Atlantic Variability Shang-Ping Xie International Pacific Research Center University of Hawaii Atlantic El Nino SST Dipole? Ocean GCM Coupled Feedback Atmospheric GCM Processes that weaken cross-eq. feedback

 x Z20 SST dipole Y_ITCZ Servain ’99, GRL

Nobre and Shukla 1996, JC

NE Brazil rainfall SST dipole Quasi-decadal oscillation? Mehta ’98, JC Tourre et al. ’99, JC Enfield et al. ’99, JGR Black et al. ’99, Science 835-year sediment core 11.4 yr

SST’ Eq 30N30S

Cloud-SST Feedback Okumura et al. ’01, GRL Xie & Saito ’01, JC

Seager et al. 2001, JC Carton et al. 1996, JPO (Hakkinen and Mo 2001, JC)  x hh  SST  ’ =0

Xie et al. 1999, GRL

Chang et al. 2000, JC Sutton et al. 2000, JC

Okumura et al. (2001), GRL SST and surface wind (JFM)

Chiang et al. 2001, JAS Obs Linear Model Corr(NCEP, Model) U V Also Chung et al. 2001, JGR

Chang et al. 2001, JC

Xie and Tanimoto ’98, GRL Zonal-mean model simulation Chang et al. ‘01, J. Climate Cross-equatorial interaction Obs

H. Okajima 2001 Processes that weaken inter-hemispheric interaction Correlation

Equatorial mode with Bjerknes feedback Meridional/dipole mode Statistical evidence Surface heat flux (wind & cloud) dominates off-eq. SST variability Near-eq. baroclinic response and barotropic teleconnection into the subtropics Two-way coupling among cross-eq. SST gradient, ITCZ, and near-eq. wind Processes that weaken this interaction: Asymmetric ITCZ and external forcing (NAO & ENSO) Conclusions