Coupled climate models project that extratropical storm tracks and eddy-driven jets generally shift poleward in response to increased CO2 concentration. Here the connection between the storm-track and jet responses to climate change is examined using the Eliassen-Palm (EP) relation. The EP relation states that the eddy potential energy flux is equal to the eddy momentumflux times the Doppler-shifted phase speed. The EP relation can be used to connect the storm-track and eddy-driven jet responses to climate change assuming 1) the storm-track and eddy potential energy flux responses are consistent and 2) the response of the Dopplershifted phase speed is negligible. Weexamine the extent to which the EP relation connects the eddy-driven jet (eddy momentum flux convergence) response to climate change with the storm-track (eddy potential energy flux) response in two idealized aquaplanet model experiments. The two experiments, which differ in their radiation schemes, both show a poleward shift of the storm track in response to climate change. However, the eddy-driven jet shifts poleward using the sophisticated radiation scheme but equatorward using the gray radiation scheme. The EP relation gives a good approximation of the momentum flux response and the eddydriven jet shift, given the eddy potential energy flux response, because the Doppler-shifted phase speed response is negligible. According to the EP relation, the opposite shift of the eddy-driven jet for the different radiation schemes is associated with dividing the eddy potential energy flux response by the climatological Doppler-shifted phase speed, which is dominated by the zonal-mean zonal wind.
Bibliographical noteFunding Information:
OL and TAS acknowledge support from NSF (AGS-1538944), and TAS is also supported by the David and Lucile Packard Foundation and the Alfred P. Sloan Foundation. The model simulations in this paper were completed with resources provided by the University of Chicago Research Computing Center. The authors thank Zhihong Tan for setting up the RRTMG radiation scheme in the idealized GCM and for helpful discussions, and two anonymous reviewers for useful comments that helped improve the manuscript.
- Atmospheric circulation
- Climate change
- Energy budget/balance
- Energy transport