This project will investigate atmosphere-ocean interactions in the tropical Pacific using a hierarchy of coupled atmosphere- ocean models of intermediate complexity. Focus will be on examination of the effects of different atmospheric models and surface boundary conditions on the interannual variability signal related to the El Nino-Southern Oscillation (ENSO) phenomenon. Besides investigating the fundamental mechanisms hypothesized to contribute to the ENSO, the project will determine the feasibility of using an improved version of the intermediate model for predicting El Nino occurrences.