Equilibrium temperature distribution and Hadley circulation in an axisymmetric model

Abstract. The impact of the equilibrium temperature distribution, θ_E, on the Hadley circulation simulated by an axisymmetric model is studied. The θ_E distributions that drive the model are modulated here by two parameters, n and k, the former controlling the horizontal broadness and the latter controlling the vertical stratification of θ_E. In the present study, variations in the θ_E distribution mimic changes in the energy input of the atmospheric system, leaving as almost invariant the Equator–poles θ_E difference. Both equinoctial and time-dependent Hadley circulations are simulated and the results compared. The results give evidence that concentrated θ_E distributions enhance the meridional circulation and jet wind speed intensities, even with a lower energy input. The meridional circulation and the subtropical jet stream widths are controlled by the broadness of horizontal θ_E rather than by the vertical stratification, which is important only when θ_E distribution is concentrated at the Equator. The jet stream position does not show any dependence with n and k, except when the θ_E distribution is very wide (n = 3) and, in such a case, the jet is located at the mid-latitudes and the model temperature clamps to forcing θ_E. Using n = 2 and k = 1, we have the formulation of the potential temperature adopted in the classical literature. A comparison with other works is performed, and our results show that the model running in different configurations (equinoctial, solstitial and time dependent) yields results similar to one another.