The maintenance and initiation of the intraseasonal oscillation has also been investigated. Analysis of the latent heat flux indicates that evaporative wind feedback and frictional wave-CISK (conditional instability of the second-kind) are not the dominant mechanisms for promoting the eastward propagation of the intraseasonal oscillation since evaporation to the west of the convection dominants. In the GLA model, enhanced evaporation tends to develop in-place over the west Pacific warm pool, while in the UKMO simulation westward propagation of enhanced evaporation is evident. It is suggested that lack of an interactive ocean may be associated with the models' systematic failure to simulate the eastward transition of convection from the Indian Ocean into the western Pacific Ocean since examination of observed sea surface temperature (SST) and its relationship to the active phase of the intraseasonal oscillation indicates that the intraseasonal oscillation may evolve as a coupled ocean-atmosphere mode. Above normal SST to the east of the convection may play a role in maintaining the eastward evolution of convection, while decreasing SSTs near the western portion of the convective envelope are associated with the cessation of convection. (pdf file).
UCRL-MI-123395