Madden-Julian Oscillation over Malay Peninsula

Signals in the intra-seasonal time scale have been extracted from 20 years of radiosonde data in ten meteorological variables over Malay Peninsula using Extended Empirical Orthogonal Function (EEOF) analyses. The first pair of EEOF modes were identified to be a manifestation of the Madden-Julian Oscillation (MJO). Interestingly, by defining a Local Multivariate MJO (LMM) index from the principal component scores, the phase of the MJO across the global tropics can be revealed. We attribute the success in capturing a global signal despite the local nature of the data to the multivariate and in-situ character of the approach. The evolution of the MJO over Malay Peninsula can be described as a succession of oscillations in the significant parameters such as zonal wind and specific humidity. The temporal and vertical structure of MJO over Malay Peninsula is further shown to be dynamically consistent. The LMM index has a low but statistically significant correlation with the local rainfall three to four pentads ahead, whereas the globally defined Real-time Multivariate MJO index does not have a significant correlation at this lead time.