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Limited hysteresis in the atmospheric dynamics of hot Jupiters

Presentation #223.10 in the session Exoplanet Atmospheres (Poster)

Published onOct 23, 2023
Limited hysteresis in the atmospheric dynamics of hot Jupiters

Over the past two decades, a coherent picture has emerged of the atmospheric dynamics of hot Jupiters from a combination of three-dimensional general circulation models (GCMs) and astronomical observations. This paradigm consists of hot Jupiters being spin-synchronized due to their close-in orbit, with a resulting large day-to-night temperature contrast. This day-to-night temperature contrast in turn raises day-to-night pressure gradients that are balanced by a circulation with wind speeds on the order of km/s. The dominant feature of this circulation is a superrotating equatorial jet, maintained by eddy-mean flow interactions that pump momentum from higher latitudes toward the equator. In this work, I explore the dependence of this circulation paradigm on the initial thermal and dynamical conditions of hot Jupiter atmospheres. To do so, I conduct MITgcm simulations of the atmospheric circulation of hot Jupiters both with varying initial wind direction and initial temperature profile. I find that the results are ubiquitously insensitive to the initial conditions, implying that the current paradigm of hot Jupiter circulation exhibits at most limited hysteresis. I interpret these results in the context of forcing regimes that have been demonstrated to lead to a bifurcation between super-rotating and sub-rotating states using a simple analytical model, and discuss implications for phase curve and eclipse map observations of hot Jupiters.

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