Title of Document: MADDEN-JULIAN OSCILLATION AND SEA SURFACE TEMPERATURE INTERACTIONS IN A MULTI-SCALE FRAMEWORK

The ocean-atmosphere coupling can play a role in initiating and sustaining the Madden-Julian Oscillations (MJOs), which are the major intraseasonal oscillations in the atmosphere. In this thesis, the oceanic influence on MJOs is studied with reanalysis products, numerical models, and idealized theoretical models. The energy sources for MJOs are calculated with NCEP reanalysis. The perturbed potential energy is found to be the most important energy source for most MJO events. In some MJO events, the sea surface is warmed due to the reduced latent heat flux during the suppressed phase of MJOs. As a result, warm sea surface temperature anomalies (SSTAs) occur, which appear to prolong the life time of these MJO events. In a minority of the MJO events, warm SSTAs can drive the atmosphere actively and trigger MJO events. In these events, the warm SSTAs are attributable to the internal oceanic processes influenced by the warm Indonesian Throughflow (ITF), which spreads from the southeastern Indian Ocean to the western Indian Ocean and modifies the subtle balance between stratification and mixing in the western Indian Ocean. In addition, during the transit period between monsoon seasons, a few MJO events ar