| We present a comprehensive assessment of the atmospheric response to multiple surface forcings in a multivariate statistical method known as the Generalized Equilibrium Feedback Analysis (GEFA). Our pilot study here focuses on the atmospheric response to major SST variability modes, such as ENSO, IMO and NAO. This pilot study confirms the dominant atmospheric response to the tropical ENSO mode of SST anomaly. This classical response to ENSO is found to consist of two parts, one responding to the tropical Pacific ENSO mode and the other to the tropical Indian Ocean Monopole mode (IOM). The Pacific ENSO generates a significant baroclinic Rossby wave response locally over the tropical Pacific as well as equivalent barotropic wave train responses remotely in the extratropics. The IOM mode forces a predominantly zonally symmetric response throughout the tropics as well as in the extratropics. Modest responses to other oceanic modes are also identified. The North Pacific SST anomaly mode appears to generate an equivalent barotropic warm SST-high response locally over the Aleutian Low and to influence the North Atlantic Oscillation (NAO) downstream, while the North Atlantic SST anomaly of tripole mode tends to force a local response on NAO. This pilot study demonstrates the potential utility of GEFA in identifying large scale oceanic influences in the observation. The potential application to a more generally combined ocean-land surface forcing and the application to the diagnosis of climate feedback in complex climate models will also be discussed. |
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