Ocean–Atmosphere Coupling on Different Spatiotemporal Scales: A Mechanism for Intraseasonal Instabilities

Abstract

The possibility of interactions between oceanic and atmospheric oscillations with different temporal and spatial scales is examined with analytical solutions to idealized linear governing equations. With a reasonable choice for relevant parameters, the mesoscale oceanic features and the large-scale atmospheric oscillations can interact with each other and lead to unstable waves in the intraseasonal band in the specific coupled model presented in this study. This mechanism is different from the resonance mechanism, which requires similar temporal or spatial scales in the two media. Instead, this mechanism indicates that even in the cases in which the temporal and spatial scales are different but the dispersion relations (i.e., functions of frequency and wavenumber) of the oceanic and atmospheric oscillations are proximal, instabilities can still be generated due to the ocean?atmosphere coupling.