FIGURE 2

Correlation coefficients (×100), mapped for global ocean Q'l+s vs. at each grid point, for the winter months, 1946-1986. Contours at 0.3, 0.5, and 0.7. Light and heavy shadings indicate correlations =0.3 and =0.5.

FIGURE 3

Difference of composites of Q'l+s (W m-2; left) and (°C mo-1; right) associated with positive (deep Aleutian Low phase) vs. negative extremes of EOF I of North Pacific SLP. Shading indicates regions where the difference exceeds the 95 percent confidence limit using a two-tailed t-test.

they are causally linked. At the centers, differences exhibit magnitudes of 0.2°C mo-1 to 0.8°C mo-1. Corresponding flux differences range from about 30 to 120 W m–2 Over the North Pacific, the PNA incorporates a swath of positive Q'l+s differences across mid-latitudes (centered at 40°N) from Asia to 140°W, and an arc of negative Q'l+s differences extending from the subtropics at 20°N, 160°E to the eastern North Pacific border, from California to the Gulf of Alaska. Downstream, the strong downstream arm of the PNA produces negative Q'l+s differences in the Gulf of Mexico and the eastern seaboard of the United States, and positive anomalies in the subtropical North Atlantic (20°N, 50°W) and east of Newfoundland. Throughout the North Pacific and North Atlantic, the PNA-associated differences mirror the flux differences, having centers co-located with the flux differences. Magnitudes of the corresponding flux and SST anomaly tendencies are consistent with typical observed mixed-layer depths, approximately 100 to 250 m in winter and 10 to 40 m in summer. Similar seasonal behavior and the relation between the flux and SST tendency are replicated in the OGCM, as presented in the following section.



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