Equilibrium temperature distribution and Hadley circulation in an axisymmetric model

Abstract

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.

Dynamics of the Hadley circulation in an axisymmetric model undergoing stratification periodic forcing

“…This approach was used by Tartaglione (2015), who used constant k values, to investigate the role of vertical stratification on the strength and position of the Hadley circulation. The response of the model atmosphere to vertical stratification will be defined by variations of the exponent k in the forcing equation as a function of time.…”

“…The response of the model atmosphere to vertical stratification will be defined by variations of the exponent k in the forcing equation as a function of time. In general, the vertical stratification can change the intensity of the Hadley cell only when the forcing is concentrated on the Equator, whereas it loses importance when the forcing is represented by a weak meridional gradient in the equilibrium temperature (Tartaglione, 2015).…”

Dynamics of the Hadley circulation in an axisymmetric model undergoing periodic change in forcing stratification

“…Observational analyses and modeling studies revealed that there are dominant periods in the tropics and subtropics. Since the publication of that paper, tropical oscillations have been extensively studied with observations (Yasunari, 1979(Yasunari, , 1980(Yasunari, , 1981Sikka and Gadgil, 1980;Yoneyama et al, 2013) as well as by means of models (Goswami and Shukla, 1984;Zhu and Hendon, 2015;Wang et al, 2016). The Madden-Julian oscillation has a significant Published by Copernicus Publications on behalf of the European Geosciences Union & the American Geophysical Union.…”