Global modes of sea surface temperature variability in relation to regional climate indices
Monique Messié and Francisco P. Chavez
Original study: Messié, M. and F.P. Chavez, 2011: Global modes of sea surface temperature variability in relation to regional climate indices. Journal of Climate, 24(16), 4313-4330. doi:10.1175/2011JCLI3941.1
Abstract: A century-long EOF analysis of global sea surface temperature (SST) was carried out and the first six modes, independent by construction, were found to be associated with well-known regional climate phenomena: the El Niño Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), the Pacific Decadal Oscillation (PDO), the North Pacific Gyre Oscillation (NPGO), El Niño Modoki and the Atlantic El Niño. Four of the six global modes are dominated by Pacific changes, the other (M2 and M6) being associated with the AMO and Atlantic El Niño, respectively. The principal component time series of the ENSO (M1) and North Pacific (M3) modes are coherent at time scales > 10 years, and their interaction results in the traditional PDO pattern and the dominant mode of Pacific multi-decadal variability. The M3 and PDO time series are well correlated but the EOFs have different spatial patterns. The fourth mode (M4) has been strengthening since the fifties and is related to the NPGO but also to El Niño Modoki especially at the decadal scale. The fifth global mode (M5) is also spatially and temporally correlated to El Niño Modoki. The Pacific SST modes are further related to atmospheric forcing, and the circulation of the North Pacific subpolar and subtropical gyres.
Data available for download: The six first principal components computed in the JClim study (M-set) are available here and updated regularly. The update is realized by projecting the updated ERSST anomalies on the original EOF maps (Fig. 1). The corresponding timeseries are plotted in Fig. 2.
|Fig. 1: Global EOF spatial patterns of the first six SST modes calculated for the 1910-2009 period. Reproduced from Messié and Chavez (2011) (Fig. 4).
hi-res image, 4mb
|Fig. 2: Time series of the principal components (PC) associated with the first six global EOF modes (1910-2009) and updated (2010-present). Time series of well correlated regional indices are superimposed. The NPGO index is negatively correlated with M4 and has been inverted. Based on Messié and Chavez (2011) (Fig. 5) and updated after 2010; both the percentage associated with each mode and the correlation with climate indices are updated to correspond to the full time series.
hi-res image, 1.2mb, time series
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