Responses of Oceanic Double-Gyre to External Wind Forcing with Noise

Stochastic resonance, in which a type of noise amplifies weak signals, has been observed in various fields, however, its oceanic applications have not been investigated in detail. Therefore, in this study, we examined basic responses of oceanic double-gyre to constant external wind forcing with noise generated by the Ornstein-Uhlenbeck equation by using a 1.5 layer quasi-geostrophic model. For cases with adequate noise, potential signals in the system appear at the front as actual signals such as intermittent large variations in energy. In addition, the flow patterns show intense meandering of strong current extension. These variations are more frequent and stronger for cases with long decorrelation time than for cases with short decorrelation time although intermittent variations can be observed even for cases with white noise.