FIGURE T22. Mean (top) and anomalous (bottom) 200-hPa stream function (CDAS/Reanalysis). Contour interval is 10 x 10⁶ m²s^-1 (top) and 5 x 10⁶ m²s^-1 (bottom). Negative (positive) values are indicated by dashed (solid) lines and the zero line is indicated by the heavy solid line. The non-divergent component of the flow is directed along the contours with speed proportional to the gradient. Thus, high (low) stream function corresponds to high (low) geopotential height in the Northern Hemisphere and to low (high) geopotential height in the Southern Hemisphere. Anomalies are departures from the 1979–95 base period monthly means.