Seasonal Synchronization in a Chaotic Ocean–Atmosphere Model

Abstract

The signatures of feedback between the atmosphere and the ocean are studied with a simple coupled model. The atmospheric component, based on Lorenz's 1984 model is chaotic and has intrinsic variability at all timescales. The oceanic component models the wind-driven circulation, and has intrinsic variability only in the decadal band. The phase of the cospectrum of atmospheric and oceanic temperatures is examined and it is found that in the decadal band, the oceanic signal leads the atmospheric one, while the opposite is true at shorter and longer timescales. The associated atmosphere-only model, driven by the oceanic temperature derived from a coupled run, synchronizes to the coupled run for arbitrary initial conditions. When noise is introduced in the time series of oceanic driving, episodic synchronization still occurs, but only in summer, indicating that control of the atmosphere by the oceanic variables is prevalent in this season.