Simultaneity of the 5 gyral waves of 1/2, 1, 4 and 8 year-periods inherited from the tropical oceans
Gyral waves are almost in phase, whatever the period. The antinodes of the biannual waves peak in March-April or September-October, and at the same places that the resonances at lower frequencies. This simultaneity is confirmed by modulated currents whose speeds are highest in May-June or November-December when they are eastward, i.e. in phase opposition with the antinodes.
As regards the annual wave antinodes are highest in November-December near the coast, regardless of the gyre. Speeds of modulated currents facing east are highest in July-August near the coast.
The period of 8 years is most appropriate for discerning antinodes due to longer wavelengths. Gyral waves are almost in phase near the coast where the antinodes are highest in average when the phase is about -2.5 years (in comparison with the signal SOI). Although noisy, the phase of the modulated current shows that the speed is maximum when it is included between 1.8 and 3.6 years, almost in opposite phase with respect to the antinode.