Equilibrium temperature distribution and Hadley circulation in an axisymmetric model

Abstract

Abstract. The impact of the equilibrium temperature distribution, θE, on the Hadley circulation simulated by an axisymmetric model is studied. The θE 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 θE. In the present study, variations in the θE distribution mimic changes in the energy input of the atmospheric system, leaving as almost invariant the Equator–poles θE difference. Both equinoctial and time-dependent Hadley circulations are simulated and the results compared. The results give evidence that concentrated θE 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 θE rather than by the vertical stratification, which is important only when θE distribution is concentrated at the Equator. The jet stream position does not show any dependence with n and k, except when the θE 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 θE. 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.