A study of the sensitivity of ENSO to the mean climate

Abstract. We study the dependence of the simulated ENSO on the mean simulated climate in the HadCM3 GCM and attempt to understand its relation with results from intermediate-complexity models (ICMs). Our aim is to bridge an existing gap between results from complex GCMs and from more readily understandable ICMs, and thereby to improve our process-based prediction skills of the potential sensitivity of observed ENSO properties (amplitude, frequency and pattern) to climate change. Although there is a suggestion that surface ENSO processes are dominating the response in HadCM3, our work also shows that the complex changes in simulated climate can have contrasting effects on the ENSO and the net result may not be robust.