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Group Meeting

Group Meeting. 2010/03/09 Kirsten Feng. ENSO and the North Pacific Gyre Oscillation: an integrated view of Pacific decadal dynamics. Di Lorenzo E., N. Schneider and K. M. Cobb, J. C. Furtado and M.A. Alexander. Goal.

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Group Meeting

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  1. Group Meeting 2010/03/09 Kirsten Feng

  2. ENSO and the North Pacific Gyre Oscillation: an integrated view of Pacific decadal dynamics Di Lorenzo E., N. Schneider and K. M. Cobb, J. C. Furtado and M.A. Alexander

  3. Goal • The aim of this paper is to quantify the decadal-scale dynamics of the Pacific and explore a conceptual framework of Pacific climate variability that relies on the connections between ocean decadal variations (e.g. PDO, NPGO), their atmospheric forcings (e.g. AL, NPO), and the ENSO cycle.

  4. Topic • North Pacific atmosphere variability: • (1) AL • (2) NPO • Ocean expression (): • (1) PDO • (2) NPGO Atmospheric forcings ocean decadal variation

  5. AR-1 Model • AR-1 model forced by SLP_PC1 and SLP_PC2 to quantify how much of the PDO and NPGO variance is explained by these atmospheric drivers:

  6. Topic • PDO • SSHa PC-1 • NPGO • SSHa PC-2 • ENSO • AR-1 model reconstruction • A. PDO (0.65) • B. NPGO (0.60) • C. SAT decadal variance (0.4~0.8) • Observation data: • SLP : NCEP/NCAR • SST : NOAA • AL & NPO forcings

  7. EOF analysis • Figure 1: 1st (left panels) and 2nd (right panels) co-variability mode of SLPa and SSTa extracted from combined EOF analysis. Each mode is characterized by an expression in SLPa, SSTa, and and a principal component (PC) timeseries that shows how these patterns are modulated in time. The PC1 (ENSO mode) and PC2 (NPGO/NPO modes) are significantly > 95% correlated to the Niño 3.4 (R=0.86) and NPGO (R=0.44) indices respectively. std=units of standard deviation.

  8. PC analysis • Figure 2: • (A) Correlation of PC1 (ENSO mode) with PC2 (NPGO/NPO modes) leading by 12 months. • (B) Temporal lagged cross-correlation function between PC1 (ENSO) and PC2 (NPGO/NPO) (black line), same for 3 year lowpass AL and NPO indices (gray line).

  9. Figure 3: (Right panels) The atmospheric projections of SEOF1 and SEOF2 referred to as SLP_PC1 and SLP_PC2 are compared to the AL (A) and NPO (B) indices. The PDOrec and NPGOrec indices are obtained by integrating SLP_PC1 and SLP_PC2 with the AR-1 model. Correlations (R) with the true indices are all signicants > 95%. Units are in standard deviations (std). (Right panels) Global SSTa reconstruction skill of AR-1 model forced with the SLP_PC1 and SLP_PC2, which are interpreted as the AL and NPO components connected to the ENSO cycle. Maps show grid point correlation between SSTa reconstruction and observations. (C) Correlation of 7 year lowpass timeseries, (D) for 2-7 year bandpass and (E) 2 year highpass.

  10. Conclusion

  11. Thank You ～ ♪ Merci beaucoup!

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