BIRS Workshop Lecture Videos
ENSO ensemble prediction for the past 161 years from 1856-2016 Liu, Ting
Several important issues of El NiÃ±o-Southern Oscillation (ENSO) predictability were studied using the latest version of the Zebiak-Cane model. A fully physically-based tangent linear model was constructed for the Zebiak-Cane model and a singular vector (SV) analysis for the 161 year (1856-2016) was performed. It was found that the leading SVs are less sensitive to initial conditions while singular values and final perturbation patterns exhibit a strong sensitivity to initial conditions. The dynamical diagnosis shows that the total linear and nonlinear heating terms play opposite roles in controlling the optimal perturbation growth. At decadal/interdecadal time scales, an inverse relationship exists between the leading singular value (S1) and correlation-based skill measures whereas an in-phase relationship exists between the S1 and MSE-based skill measures. However, S1 is not a good predictor of prediction skill at shorter time scales and for individual predictions. An offsetting effect was found between linear and nonlinear perturbation growth rates, which have opposite contributions to the S1. Ensemble and probabilistic ENSO predictions were performed for the 161 yrs. Results suggest that â reliabilityâ is more sensitive to choice of ensemble construction strategy than â resolutionâ . The strategy produces the most reliable and skillful ENSO probabilistic prediction, benefiting from the contribution of the stochastic optimal winds and singular vector of SSTA.
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