ENSO flavors and oceanic background conditions in the NCAR-CCSM4

El Niño-Southern Oscillation (ENSO) is a fundamental component of the climate system due to its profound impact upon the global climate. Over the last few years a large literature has described a type of El Niño in which the maximum sea surface temperature (SST) anomalies are located in the central equatorial Pacific rather than in the eastern Pacific, as in the canonical ENSO. Different centers of warming are associated with different teleconnection patterns and impacts. For example, surface temperature and precipitation anomalies over North America, India and Australia are strongly dependent upon the longitudinal position of the SST anomalies along the equatorial Pacific. Improved understanding of the connection between ENSO flavors and the background oceanic state can help identifying possible precursors of these events, elucidate their underlying dynamics, and provide insight on their predictability. Here we examine the relationship of ENSO flavors with background conditions in a 500-year control simulation of the National Center for Atmospheric Research Community Climate System Model version 4 (NCAR-CCSM4), a state-of-the-art climate model with a relatively realistic simulation of tropical Pacific interannual variability. The ratio between central and eastern Pacific warm events is in agreement with what estimated from the observational record. Results show a statistically significant correlation between intense ENSO activity in the eastern and central Pacific.