Evidence of cooperative interactions between intraseasonal oscillations and equatorial waves

A multiple linear model that includes the first through fourth powers of an OLR time series index of the ISOe as predictors of precipitable water anomaly data (PW) filtered in wavenumber and frequency for two bands representing the ISOe and the ISOw is described. The results show that the model with nonlinear terms is more similar to the independent composite than is the simple linear model. A discussion of the structure of the contribution of the nonlinear terms, showing that the nonlinear terms model interactions by which the ISOe modulates the amplitude and other behaviors of the ISOw is presented. The results also show that the collinearities between the set of predictors do not significantly affect results for this application of the model form.