Variability of the Madden-Julian Oscillation (MJO)

The Madden-Julian Oscillation's (MJO) role in intraseasonal climate variability on the global scale provides a critical starting point for operational extended range forecasts (2-4 weeks). The influence of the MJO extends to the timing of monsoons, phasing and intensity of the El Niño-Southern Oscillation (ENSO), termination of the Indian Dipole, and extension of the East Asian jet stream. The MJO has also been found to modulate a host of mid-latitude weather phenomena including precipitation and circulation, which then impact smaller-scale phenomena such as air quality and tornado activity. The MJO has even been connected to intraseasonal changes in Arctic sea ice. These many teleconnections and the increasing use of MJO forecasts in real time suggest that further investigation into the variability of the MJO itself is needed. For example, strong seasonality of the MJO may account for a decrease in current ensemble accuracy in forecasts greater than approximately 5 days. Current knowledge of seasonal variability is limited to magnitude peaks and does not address changes in period of individual MJO phases. To increase understanding and aid predictions of the MJO, this study will examine temporal progressions of the MJO between all phases. Length of each phase will be examined with historical data (1974 – present) from the commonly used Real-time Multivariate MJO (RMM) index. These results will be compared to variations during ENSO phases, seasonal changes, and other intraseasonal MJO-like events. Finally, recently developed MJO indices will be explored and compared to the RMM related results.