Multi-model Intraseasonal Forecasting of the Madden-Julian Oscillation during DYNAMO/CINDY/AMIE Period

The present study assessed the forecast skill of the Madden-Julian Oscillation (MJO) observed during the DYNAMO/CINDY/AMIE Intensive Observing Period (IOP, from October 1st, 2011 to January 15th, 2012) in conventional weather and climate general circulation models and revealed their strengths and weaknesses in forecasting the initiations and propagations of the MJO. In general, current models have higher skills in forecasting the MJO that follows a preceding event (successive MJO) than that with no preceding event (primary MJO). The common modeling problems include: i), too slow eastward propagation; ii), the Maritime Continent barrier; and iii), the difficulty to predict the primary events. More specifically, it is found that the MJO forecasting skills during the IOP, measured with the Wheeler-Hendon Index, reach 12, 21, and 28 days for the GFS atmosphere-only model, the CFSv2 and UH coupled models, respectively. This result demonstrates that air-sea coupling extends MJO predictability by at least one week. Comparative analysis of the CFSv2 and UH coupled models indicates that the propagation speed of the models' intrinsic MJO mode is critical for the forecast performance. Further numerical experiments have been carried out to reveal the roles of SST feedback and atmospheric internal dynamics on MJO initiation and propagation.