Observational Analysis of the Multiscale Dynamics in the Madden-Julian Oscillation

The 20–90-day Madden-Julian oscillation (MJO) dominates the tropical intraseasonal variability while interacting with tropical and extra-tropical weather and climate systems. It exhibits multiscale characters in space and time as a result of nonlinear and stochastic interactions among its component cloud systems and hierarchical regulations imposed by the atmospheric and oceanic environment. With a set of methodologies that extract chaotic signals in the ubiquitous background noise, Tung et al. (2011) has characterized the MJO as a stochastically-driven chaotic oscillator using ~30-year-long observation-based MJO index time series. The stochastic forcing may well be exerted by the multiscale cloud populations and the related organizing processes. The satellite-derived deep convective index during the TOGA-COARE IOP (November 1992 to February 1993) has suggested that the convective activities of lifetimes ranging from 1 hour to ∼21 days have interdependence across scales that can be described by a series of power laws, i.e., multi-fractal scalings (Tung et al. 2004). The evolution of cloud systems within an MJO event was studied from initiation over the Indian Ocean to demise near the date line. In the current study, we further develop a temporal-spatial analysis of the stochastic forcing, emphasizing the notion of persistent correlations using the fractal theory, first with the ~10-year precipitation based on the Tropical Rainfall Measuring Mission (TRMM), then with the ERA Interim reanalysis in the comparable time period. Heat and moisture budgets are to be computed with the ERA Interim and analyzed. It is anticipated that the analysis will enable a more comprehensive understanding of the temporal-spatial convective system dynamics associated with the MJO, as well as facilitate DYNAMO observation-driven modeling of the MJO.