Abstract
Predictability time scales are estimated from annual time series of the El Niño/Southern Oscillation (ENSO). They we defined by the rate of divergence of initially close independent pieces of trajectories in phase space. Fitted stochastic processes and the nonlinear deterministic analysis of the empirical time series lead to e-folding predictability time scales up to 1.5 years (or one year of error doubling time) indicating that at least a skillful nowcasting of ENSO may be possible. Due to sparse data these estimates provide only weak bounds.
