On the role of anomalous ocean surface temperatures for promoting the record Madden-Julian Oscillation in March 2015

A Madden-Julian Oscillation (MJO) event dramatically amplified at the beginning of March 2015 as the convective phase traversed an unusually warm central Pacific Ocean. This record amplification also resulted in record amplitude of the MJO based on index measurements since 1974. We explore the possible role of the anomalously high ocean surface temperatures in the equatorial central Pacific for promoting the extraordinary amplification of this MJO event. Forecast sensitivity experiments with the Predictive Ocean Atmosphere Model for Australia show that the enhanced growth of the MJO resulted from amplification of the convective anomaly as it encountered the unusually warm central Pacific. Our results indicate that anomalous sea surface temperature (SST) at the onset of El Nino 2015 promoted the intensification of the MJO. We suggest a two-way interaction whereby initial SST anomalies promoted enhanced MJO activity which then possibly led to enhanced El Nino development.