Origins of the midlatitude Pacific decadal variability

Analysis of multiple climate simulations shows much of the midlatitude Paci fic decadal variability to be composed of two simultaneously occurring elem ents: One is a stochastically driven, passive ocean response to the atmosph ere while the other is oscillatory and represents a coupled mode of the oce an-atmosphere system. ENSO processes are not required to explain the origin s of the decadal variability. The stochastic variability is driven by rando m variations in wind stress and heat flux associated with internal atmosphe ric variability but amplified by a factor of 2 by interactions with the oce an. We also found a coupled mode of the ocean-atmosphere system, characteri zed by a significant power spectral peak near 1 cycle/20 years in the regio n of the midlatitude North Pacific and Kuroshio Extension. Ocean dynamics a ppear to play a critical role in this coupled air/sea mode.