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Mechanisms governing interactions between the Madden–Julian Oscillation (MJO), Kelvin wave activity, and El Nino development are reexamined using the oceanic component of the Zebiak–Cane (ZCocn) model of the Pacific basin. Prescribed wind stress from a free run of the super-parameterized Community Climate System Model version 4 (SP-CCSM4) is used to force ZCocn and the simulated El Nino events are analyzed with respect to their relationship with the MJO wind forcing. Composites of El Nino events strongly influenced by the MJO show the earlier onset of a flattened, El Nino-like state of the thermocline. In contrast, the composites of El Nino events not influenced by the MJO winds show a later onset, and are dominated by a transient-like thermocline along with periods of upwelling Kelvin wave activity. Sensitivity experiments performed to identify whether modifying MJO wind stress and oceanic Kelvin wave activity influences these features show that although MJO contributes to the development of these features, it is not necessarily the primary driver. The relative phasing between MJO and oceanic Kelvin wave activity seems to be the most important factor governing the influence of MJO on El Nino. When in phase and collocated with Kelvin wave activity, MJO westerly wind stress contributes to the amplification of preexisting downwelling Kelvin waves, leading to earlier onset and greater strength of the resulting El Nino events. The out-of-phase interactions between MJO and oceanic Kelvin waves explain the observed lack of influence of MJO onto some El Nino events.

The energy budget of the Pacific Ocean is evaluated in the Super-Parameterized Community Climate Model version 4 (SP-CCSM4) on intraseasonal time scales. The budget terms are decomposed to isolate the MJO influence and the ocean current associated with Kelvin waves. Using this decomposition, one can distinguish between El Nino events with strong and weak MJO influence. Composites of El Nino events based on the wind power component associated with the MJO induced wind stress and oceanic Kelvin waves ( $${{\text{W}}_{{\text{MJO}},{\text{K}}}}$$ ) are compared with composites based only on the atmospheric variability and based only on the oceanic variability. It was found that the composite of events when $${{\text{W}}_{{\text{MJO}},{\text{K}}}}$$ is near maximum (+ NMJO,K) shows a greater magnitude of mean perturbation wind power, buoyancy power, and available potential energy than any other case, which is consistent with the greater amplitude Kelvin wave perturbations on the thermocline, as well as the greater amplitude of SST anomalies at the peak of the event. For + NMJO,K, latent heat flux anomalies out of the ocean along the coast of New Guinea are seen coincident with deepening of the mixed layer depth there, suggesting that this is an important region for the thermodynamic influence of the MJO on the ocean. Latent heat flux anomalies into the ocean are seen across the ITCZ in the spring, suggesting a basin wide influence by the MJO on the ocean surface radiation budget in + NMJO,K.