This figure shows the empirical orthogonal functions (EOFs) of monthly-mean 500 millibars geopotential height corresponding to the observed PNA-like pattern in the North Pacific region during 4 winter months (December-March) for different datasets:

    1. ACYC (CCM3 forced by annual cycle of climatological SST);
    2. TOGA (CCM3 forced by observed tropical monthly-mean SST variability);
    3. GOGA (CCM3 forced by observed global monthly-mean SST variability);
    4. COUP (CSM coupled integration); and
    5. NCEP (NCEP/NCAR Reanalysis of observational data).
The non-dimensional normalized EOFs have been multiplied by the square-root of the corresponding EOF variance to show the dimensional standard-deviation of Z500 at each grid-point associated with the EOF. The EOF number and the fractional variance associated with it are shown in the figure titles. Contour interval = 20m.