Possible Unstable Periodic Orbits of Tropical Intraseasonal Oscillations

The rainfall over India during the boreal summer exhibits two leading nonlinear monsoon intraseasonal oscillations (MISOs) with broad-band spectra centered at 45 and 28 days. The active-break cycle within the monsoon season is mostly defined by the two leading MISOs. The first MISO is considered to be the summer equivalent of the Madden-Julian Oscillation (MJO) which is more dominant during the boreal winter. This study explores the possible existence of unstable periodic orbits embedded in the nonlinear MISOs and MJO that are extracted by applying multi-channel singular spectrum analysis. Using the methods of nonlinear dynamical systems, this study attempts to extract the unstable periodic orbits from the data of MISOs and MJO. The routes through which these unstable periodic orbits may lose stability are investigated.