Figure 6

MRI_cgcm_2_3_2 20thc run 1: No statistically significant stadium-wave signature. (a) Two plots are given. The first is the M-SSA spectrum for this model. No modes fall outside the red-noise envelope and no modes are well-separated from others; thus no significant mode can be identified. The second plot in (a) shows the cumulative variance accounted for by the first twenty modes. (b) Shows the RCs of individual modes one through seven. (c) Shows the statistically non-significant “stadium-wave-like” propagation of normalized RCs of joint modes one and two. Many caveats are attached to this “wave”, lack of statistical significance being only one. The spatial pattern differs from the original stadium wave, with ALPI non-aligned with NPO and PDO as an example. Temporal character of NINO is unlike that of the original ‘wave’. For the entire mri_20thc ‘wave’, time scale of variability progressively increases as signal progresses through the time series. Sequence of signal propagation appears to fall apart with time.