Off-campus University of Miami users: To download campus access dissertations, please use the following link to log into our proxy server with your University of Miami CaneID and Password.
Non-University of Miami users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
UM campus only
Doctor of Philosophy (PHD)
Meteorology and Physical Oceanography (Marine)
Date of Defense
First Committee Member
Second Committee Member
Third Committee Member
Brian E. Mapes
Fourth Committee Member
A parameterization is designed to study the role of Madden-Julian Oscillation (MJO) and the modulation by sea surface temperature (SST) in El Niño—Southern Oscillation (ENSO). It is added to a coupled ocean-atmosphere model of intermediate complexity and to a coupled general circulation model (CGCM) that does not any generate internal MJO. The MJO parameters acquire values either additively, i.e. randomly from observed distributions, or multiplicatively, i.e. modulated by evolving model ENSO-SST, albeit with some stochasticity. Sensitivity tests using the intermediate model reveal the complexity of MJO-ENSO relationship: e.g. ENSO strengthens with increase in either the stochasticity of amplitude or the degree of its SST-modulation, but similar relationships are not evident for speed and zonal extent. Ensemble comparisons between simulations with and without SST-feedback suggest that SST feedback to the MJO acting in a stable regime can be responsible for the observed ENSO variance. The multiplicative case has a larger ensemble spread than the additive case, which manifests in a larger interdecadal variability of ENSO. Long-term simulations of the CGCM reveal that although the unrealistic 2-yr ENSO period is retained upon the inclusion of additive or multiplicative MJO, there is a disruption in the biennial regularity of ENSO. The timing and occurrence of El Niños become dependent on the timing of MJO activity, which manifests in unseasonal ENSO peaks and reduced interannual power. These constraints on El Niño are linked to the seasonal curtailment of eastward propagating upper ocean anomalies by the easterlies that intersperse MJO westerlies. The power is partially restored in the multiplicative case, where the enhancement of MJO westerlies during warming phase leads to stronger subsequent peaks. Re-simulations performed by switching the MJO presence or SST-dependence at a strategically chosen time demonstrate that the SST-feedback to the MJO has almost as much impact on the evolution of ENSO anomalies as the random component of the MJO.
Kapur, Atul, "Role of Madden-Julian Oscillation and Its Modulation by the Sea Surface Temperature in El Niño—Southern Oscillation" (2013). Open Access Dissertations. 1123.