Models of the predictability of a simple nonlinear dynamical system

Chaotic nonlinear low order systems are often regarded as paradigms of the atmospheric behaviour, not least because of their limited predictability. In this paper, the predictability of a forced nonlinear system proposed by Lorenz is examined. The system is a compelling heuristic model of the mid-latitude global circulation; it exhibits limited predictability. While weak error growth takes place throughout most of the phase of the system, strong error growth is confined to very limited regions of phase space. A "discrete scattering" model of error growth is proposed. (C) 2002 Royal Meterological Society