Time evolution of the energies in each mode ﹩{E}_{j}={A}_{j}{A}_{j}^{* }﹩, j = 1, 2, 3, of Triad a, for the forced/dissipative case (left panel) and for the conservative case (right panel), over a 10,000 year period. One observes long-term modulations with timescales of several hundred/thousand years on the amplitude peaks of the main ∼10 yr cycle in the case with forcing and dissipation. One notices in this case the occurrence of periods of very low energy of the three wave modes, whereas for conservative case (right panel) one does not observe such periods.