Fast and Slow Components of the Extratropical Atmospheric Circulation Response to CO2 Forcing

Fast and slow components of the extratropical atmospheric circulation

Poleward shifts of the extratropical atmospheric circulation are a common response toCO2 forcing in global climate models (GCMs), but little is known about the time dependence of this response. Here it is shown that in coupled climate models, the long-term evolution of sea surface temperatures (SSTs) induces two distinct time scales of circulation response to steplike CO2 forcing. Inmost GCMs f...

Isentropic Slopes, Downgradient Eddy Fluxes, and the Extratropical Atmospheric Circulation Response to Tropical Tropospheric Heating

Climate change experiments run on Intergovernmental Panel on Climate Change (IPCC)–class numerical models consistently suggest that increasing concentrations of greenhouse gases will lead to a poleward shift of the midlatitude jets and their associated eddy fluxes of heat and potential vorticity (PV). Experiments run on idealized models suggest that the poleward contraction of the jets can be t...

Probing the Fast and Slow Components of Global Warming by Returning Abruptly to Pre-Industrial Forcing

The fast and slow components of global warming in a comprehensive climate model are isolated by examining the response to an instantaneous return to pre-industrial forcing. The response is characterized by an initial fast exponential decay with an e-folding time smaller than 5 years, leaving behind a remnant that evolves more slowly. The slow component is estimated to be small at present, as me...

Extratropical forcing of ENSO

Atmospheric Gcm Response to Extratropical Sst Anomalies: Synthesis and Evaluation

We examine the advances in our understanding of extratropical atmosphere-ocean interaction over the past decade and a half, focusing on the atmospheric response to sea surface temperature anomalies. The main goal of the paper is to assess what was learned from general circulation model (GCM) experiments over the recent two decades or so. Observational evidence regarding the nature of the intera...