ENSO and Pacific Decadal Variability in Community Climate System Model Version 4

Several aspects of ENSO are improved in CCSM4 compared to its predecessor CCSM3, including the lengthened period (3-6 years), the larger range of amplitude and frequency of events, and the longer duration of La Nina compared to El Nino.

However, the overall magnitude of ENSO in CCSM4 is overestimated by -30%. The simulated ENSO exhibits characteristics consistent with the delayed/recharge oscillator paradigm, including correspondence between the lengthened period and increased latitudinal width of the anomalous equatorial zonal wind stress. Global seasonal atmospheric teleconnections with accompanying impacts on precipitation and temperature are generally well simulated, although the wintertime deepening of the Aleutian Low erroneously persists into spring.