El Niño‒Southern Oscillation (ENSO) is the dominant mode of tropical interannual climate variability. It arises from atmosphere-ocean interactions in the tropical Pacific and is associated with large anomalies of sea-surface and sub-surface temperatures, zonal winds and rainfall. The main defining properties of an ENSO event are its spatial structure, amplitude, periodicity, seasonality and the spatial and temporal asymmetries. These ENSO properties are influenced by many processes internal to the Pacific basin, as well as by inter-basin and tropical-extratropical interactions.

            In this presentation, we will examine the major ENSO properties as simulated by the recently developed Australian Community Climate and Earth System Simulator version 2 (ACCESS-CM2). ACCESS-CM2 has been developed over the last few years for participation in the upcoming Coupled Model Intercomparison Project phase 6 (CMIP6), with the CABLE land surface scheme being implemented in the latest version of the model. We will compare the ENSO properties simulated by this model with those calculated from observations and also investigate how these properties are influenced by the tropical atmosphere-ocean interaction processes. The aim is to document the model performance and biases in ENSO simulation and to understand better the origin of these biases using conceptual models incorporating fundamental ENSO processes. Such an understanding is expected to help further improve the ENSO simulations in future versions of the ACCESS and other coupled models.