interactive ensemble model을 이용한 기후연구

Abstract

The debate on the role of noise continues because most of our understanding is based on relatively simple models that include stochastic forcing processes in an ad hoc manner and/or oversimplify the nonlinear dynamics and coupling. The relative importance of stochastic forcing versus deterministic coupling has not been analyzed within the context of coupled general circulation model (CGCM). Here we introduce a new coupling strategy, so called interacitve ensemble, for isolating the impact of the weather noise due to internal atmospheric dynamics. The interactive ensemble model has six realizations of the atmosphere GCM (AGCM) coupled to a single realization of the ocean GCM (OGCM). As the interactive ensemble evolves, each AGCM realization experiences the same sea surface temperature (SST) predicted by the OGCM. The OGCM, on the other hand, experiences surface fluxes that are the ensemble average of the six AGCM realizations. In this paper we study the impact of tropical internal atmospheric variability on the North Pacific SST variability through an idealized interactive ensemble experiment. An enhanced tropical internal atmospheric variability contributes to strengthen and broaden the western North Pacific SSTA variability including the Kuroshio extension via the atmosphere teleconnections. This result supports the notion that the tropics play an active role to change the North Pacific SST variability via the atmospheric teleconnections. It is also suggested that the noise due to internal atmospheric variability causes the modulation of ENSO, which in turn influences the North Pacific SSTA variability via the atmosphere teleconnections.