Predictability of the Madden Julian Oscillation (MJO) in the Intraseasonal Variability Hindcast Experiment (ISVHE)

Being the prominent physical mode of tropical intraseasonal variability, the Madden-Julian Oscillation (MJO) represents a primary source of predictability on the intraseasonal timescales. With its influence extending over multitude time and space scales, efforts for predicting the MJO has been a focus of intense research for the past two decades. While the last decade has witnessed marked improvement in dynamical MJO prediction, timely assessment of the practical and potential MJO prediction capabilities in dynamic models is crucial for guiding future research and development priorities. In this study, the predictability of winter MJO is investigated based on the Intraseasonal Variability Hindcast experiment (ISVHE), a set of dedicated extended range hindcasts from eight different coupled models. MJO predictability is estimated from both the deterministic and ensemble mean hindcasts, giving values of 20-30 days and 35-45 days, respectively, for most of the models examined. The fact that the model's hindcast skill is less than the estimated predictability limits by about 5-7 days, suggests that more skillful MJO forecasts can be afforded through further improvements of dynamical models. In addition, analysis of the 'spread - error' relationship in the different ensemble prediction systems (EPS) indicates that significant improvements in MJO prediction can also be brought out through focused improvements in the existing EPSs.