Atmospheric bistability and abrupt transitions to superrotation: wave-jet resonance and Hadley cell feedbacks

Abstract

Strong eastward jets at the equator have been observed in many planetary atmospheres and simulated in numerical models of varying complexity. However, the nature of the transition from a conventional state of the general circulation, with easterlies or weak westerlies in the tropics, to such a superrotating state remains unclear. Is it abrupt or continuous? This question may have far-reaching consequences, as it may provide a mechanism for abrupt climate change in a planetary atmosphere, both through the loss of stability of the conventional circulation and through potential noise-induced transitions in the bistability range. We study two feedbacks which may lead to bistability between a conventional and a superrotating state: the Hadley cell feedback and a wave-jet resonance feedback. We delineate the regime of applicability of these two mechanisms in a simple model of zonal acceleration budget at the equator. Then, we show using numerical simulations of the axisymmetric primitive equations that the wave-jet resonance feedback indeed leads to robust bistability, while the bistability governed by the Hadley cell feedback, although observed in our numerical simulations, is much more fragile in a multilevel model.

References in corpus (9)

• Equatorial superrotation on tidally locked exoplanets
• Atmospheric dynamics of Earth-like tidally locked aquaplanets
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• Random changes of flow topology in two dimensional and geophysical turbulence
• The Transition to Superrotation in Terrestrial Atmospheres
• A rare event algorithm links transitions in turbulent flows with activated nucleations
• Experimental evidence of a phase transition in a closed turbulent flow
• Forcing-dependent stability of steady states in a turbulent swirling flow
• Bifurcations of a large scale circulation in a quasi-bidimensional turbulent flow

Cited by in corpus (8)

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• The Acceleration of Superrotation in Simulated Hot Jupiter Atmospheres
• Discontinuous Transitions Towards Vortex Condensates in Buoyancy-Driven Rotating Turbulence
• Collapse of transitional wall turbulence captured using a rare events algorithm
• Phase Shift of Planetary Waves and Wave--Jet Resonance on Tidally Locked Planets
• Does rare, noise-induced, bypass transition in plane Couette flow bypass instantons ?
• Irreversible energy extraction from negative temperature two-dimensional turbulence