2025/02/26 by Thaddeus D. Komacek, Komacek, Thaddeus D. · 2 voices
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #Stellar, planetary, and galactic studies #astro-ph.EP #physics.ao-ph
paper · pdf · doi:10.48550/arxiv.2502.19394
openalex publication_date 2025/02/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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 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 superrotating 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.