Limited Hysteresis in the Atmospheric Dynamics of Hot Jupiters

Journal article

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 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 irradiation gradient driving a 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−1. The dominant feature of this circulation is a super-rotating equatorial jet, maintained by eddy-mean flow interactions that pump momentum into the jet. In this work, I explore the dependence of this circulation paradigm on the initial thermal and dynamical conditions in atmospheric circulation models of hot Jupiters. To do so, I conduct MITgcm simulations of the atmospheric circulation of hot Jupiters with both varying initial wind directions and initial temperature profiles. I find that the results are insensitive to the initial conditions, implying that the current paradigm of hot-Jupiter circulation exhibits at most limited hysteresis. I demonstrate that there is a single characteristic wind speed of hot Jupiters for given planetary and atmospheric parameters using an idealized scaling theory, and discuss implications for the interpretation of hot Jupiter observations.

Authors: Komacek, TD

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 983
• Issue: 1
• Article number: 7
• Publication date: 2025-04-01
• Acceptance date: 2025-02-25
• DOI: 10.3847/1538-4357/adbae9
• EISSN: 1538-4357
• ISSN: 0004-637X
• Language: English
• Keywords: Exoplanet atmospheric dynamics; Hot Jupiters; Exoplanet atmospheres; Planetary atmospheres