Ocean-Atmosphere Interaction and the Excitation of Low Frequency Variability by Nonlinear Fluxes of Energy

Low-frequency variability of the climate system can be excited by both internal, nonlinear processes and external forcing. Partitioning the climate's responses to these forcings is an important and challenging problem, particularly with respect to nonlinearities across vast time and spatial scales. Recent studies have shown that high frequency nonlinear interactions within an ocean system can excite variability on longer timescales. This indicates an inverse cascade of energy in frequency space similar to the familiar cascade across spatial dimensions. We show preliminary results on the presence of a temporal inverse cascade within a state-of-the-art realistic-domain high-resolution coupled atmosphere-ocean model and discuss the potential implications of this cascade on coupled modes of low-frequency variability.