Fig. 5: Changes in u*v* convergence associated with the EMF.

As in Fig. 1, except that the momentum flux (\({u}^{* }{v}^{* }\)) at 700 hPa is regressed against (a, b) EMFI, c, d NH PC2, and (e, f) NH PC1. The left panels show calculations based on the planetary momentum flux, which is derived from the interaction between the zonal and meridional winds of zonal wave numbers \(k\le 3\). The right panels show calculations based on the synoptic momentum flux, the interaction between the zonal and meridional winds for zonal wave numbers \(k\ge 4\). Changes in storm track activity are overlaid with contours.