Rotated global modes of non-ENSO sea surface temperature variability

A varimax rotation was applied to the EOF modes of global SST derived by En field and Mestas-Nunez. The SST anomaly record is more than a century long, with a global complex EOF representation of ENSO and a linear trend remove d at every grid point. The rotated EOF modes capture localized centers of v ariability that contribute to the larger-scale spatial patterns of the unro tated modes. The first rotated EOF represents a multidecadal signal with la rger. response in the North Atlantic. The second rotated EOF represents an interdecadal fluctuation with larger response in the eastern North Pacific and out of phase fluctuations of smaller amplitude in the central North Pac ific. The third rotated EOF captures interdecadal fluctuations in the easte rn tropical Pacific with a dominant peak that coincides with the 1982/83ENS O. The fourth rotated EOF has interdecadal to multidecadal nature with larg er response in the central equatorial Pacific and quasi-symmetric out-of-ph ase response in the western North and South Pacific. The fifth mode represe nts multidecadal fluctuations with large response at about 40 degrees N in the North Pacific. The sixth mode has interannual to interdecadal timescale s with largest response confined to the South Atlantic. The authors' rotate d modes are dominated by intra- rather than interocean fluctuations support ing the hypothesis that the non-ENSO variability is more regional than glob al in nature. Analyses of sea level pressure and surface wind stress show t hat in general the nan-ENSO rotated EOFs are consistent with an ocean respo nse to local atmospheric forcing. An exception is the eastern tropical Paci fic mode, which is more consistent with an atmospheric response to changes in the ocean SST.