Fig. 12
East–west or azimuthal (\(u_\phi\)) component of the quasi-geostrophic flow at \(40^{\circ }\hbox {W}\), on the equator. The time average has been subtracted from each flow realization so that only the time-varying part is shown (the mean time-averaged value for this location was −18.3 km/year, and the standard deviation 3.5 km/year) and the flow has been truncated at degree 16 as in the previous figure. Example realizations from the ensemble of flow solutions are shown in grey, while the ensemble mean flow is shown in black. Note that SA extrema (pulses) occur at this location in approximately 2005.8, 2009 and 2013.5, corresponding to times of large azimuthal flow acceleration, in between maxima and minima of \(u_\phi\)