The application of the real-time multivariate Madden-Julian Oscillation Index to intraseasonal rainfall forecasting in the mid-latitudes

The application of the real-time multivariate Madden-Julian Oscillation Index to intraseasonal rainfall forecasting in the mid-latitudes

The Madden-Julian Oscillation is a tropical atmospheric phenomenon detected as anomalies in zonal winds, convection and cloudiness. This perturbation has a definitive timescale of about thirty to sixty days, allowing its signal to be extracted from background data. The Madden-Julian Oscillation originates over the western Indian Ocean and generates a convective region which moves east along the equatorial region. This perturbation is thought to contribute to the timing and intensity of the eastern hemisphere monsoons, the El Niño/ Southern Oscillation and tropical storms and cyclones. The current understanding of the Madden-Julian Oscillation is that it restricts the bulk of its' influence to the tropics, however some evidence suggested that the impact is more extensive. Analysis of about 30 years of data showed significant modulation of rainfall by the equatorial passage of the MJO. The real-time multivariate Madden-Julian Oscillation Index was used to estimate the location and amplitude of the Madden-Julian Oscillation, and forms the basis of the basic rainfall prediction tool developed. The method developed here clearly linked the low latitude passage of the Madden-Julian Oscillation with suppressed and enhanced rainfall events in the Australasian region and beyond. A rudimentary forecasting capability at the intraseasonal time scale has been developed suitable for assisting Australian agricultural sector. A subsequent and independent analysis of global mean sea level pressure anomalies provided evidence of teleconnections between the Madden-Julian Oscillation and higher latitude atmospheric entities. These anomalies confirm the existence of teleconnections capable of producing the rainfall pattern outputs. The MJO is strongly influenced by the season. However the seasonally dependant analysis of rainfall with respect to the Madden Julian Oscillation conducted was inconclusive, suggesting aspects of the MJO influence still require clarification. Considering the importance of rainfall variability to the Australian agricultural sector the forecasting tool developed, although basic, is significant.