Toward linking weather and climate in the interactive ensemble NCAR climate model

Abstract

Diagnosing how much low frequency climate variability is due to intrinsic coupled (i.e., interactions among the components of the climate system) modes and how much is stochastically forced by internal dynamics (e.g., weather noise forcing ocean variability or ocean dynamics associated with western boundary current forcing atmospheric variability) remains a challenge in climate research. Here we present a methodology for separating the intrinsic coupled modes from the stochastically forced variability that can be applied at the air-sea, air-land, air-ice or ice-ocean interface. In the results presented here, we focus on the air-sea interface and apply the approach to the National Center for Atmospheric Research Community Climate System Model. We find that coupled oceanatmosphere feedbacks contribute to a significant fraction of the sea surface temperature variability worldwide with increasing importance in the tropics. One of the by-products of the experiments presented here is an improved diagnostic tool for understanding atmospheric teleconnections. In this regard, we find that the mid-latitude atmospheric response to tropical forcing is not simply a function of the magnitude of the forcing. Copyright 2009 by die American Geophysical Union.