Local and Remote Impacts of Atmospheric Cloud Radiative Effects Onto the Eddy-Driven Jet

This study examines the cause of the spread of extratropical circulation responses to the inclusion of atmospheric cloud radiative effects (ACRE) across atmospheric general circulation models. The ensemble of Clouds On-Off Klimate Intercomparison Experiment aquaplanet simulations shows that these responses include both equatorward and poleward shifts of the eddy-driven jet of varying magnitudes. These disparate extratropical responses occur despite the relatively consistent response in the tropics: a heating in the upper troposphere, which leads to a strengthening of the Hadley cell. It is argued that the eddy-driven jet response is a competition between two effects: the local influence of clouds driving shifts of the jet through meridional gradients in ACRE and the remote impact of a strengthened Hadley cell causing an equatorward shift of the eddy-driven jet. Simulations in which cloud radiative effects are separately turned on in the tropics and extratropics demonstrate this explicitly.