What Can We Learn on the Predictability of Coupled Ocean-Atmosphere Systems from Low-Order Modelling?

Abstract:

Multi-scale low-order models can provide insight on the dynamics and predictability of systems possessing components displaying very different time and/or space scales. Recently we have developed a hierarchy of low-order coupled ocean-atmosphere models of different complexity, allowing to clarify the impact of the mechanical coupling and radiative transfers between the ocean and the atmosphere on the dynamics and predictability of this multi-scale system. In this presentation we review past and recent results as obtained with this type of low-order models. In particular we will show that slow coupled modes emerge for large mechanical couplings, inducing a reduction of the mean meridional thermal gradient. This in turn reduces drastically the instability properties of the coupled flow.