We thank Paul O’Gorman for performing the simulations without ocean heat transport and for helpful comments and discussions. We are grateful for support by the National Science Foundation (Grants ATM-0450059 and AGS-1019211), the Davidow Discovery Fund, and a David and Lucile Packard Fellowship. The simulations were performed on the Division of Geological and Planetary Sciences’s Dell cluster at the California Institute of Technology. The program code for the simulations described in this paper, and the simulation results themselves, are available from the authors upon request.
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The values for α are 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.5, 3.0, 4.0, and 6.0.
These results contradict the hypothesis of Trenberth and Stepaniak (2003), according to which extratropical eddy heat fluxes were posited as a driver of the Hadley circulation. In our simulations, changes in the strength of the Hadley circulation between ocean simulations and slab simulations are not accompanied by changes in extratropical eddy heat fluxes that are nearly as large, and the total heat flux is not necessarily “seamless” in the subtropics.