IMPACT OF THE SEA SURFACE TEMPERATURE ON THE ATMOSPHERE RESPONSE: MONTHLY FORECASTING OF THE MADDEN-JULIAN OSCILLATION

摘要

The ECMWF monthly forecasting system is used for the forecast of the Madden-Julian Oscillation (MJO) event of the winter 1992-1993. The impact of the oceanatmosphere coupling on the MJO forecast skill is assessed in parallel with sensitivity tests on the temporal resolution (daily, weekly and monthly) of Sea Surface Temperature (SST) forcing fields. The coupling to the ocean provides a better MJO forecast than the current operational system that persists SST anomalies. The coupling also appears as a good alternative to forcing by montlhy SST but it is still not better than forcing by weekly or daily SST, probably because of the drift of the ocean model. Forcing with weekly ERA interim SST provides a better forecast than forcing with OSTIA daily SST. This unexpected result raises the question how the mean state and the time variability of the ocean surface matter for the MJO forecast.