Angular Momentum and Heat Transport on Tidally Locked Hot Jupiter Planets

TL;DR

This study uses a 3D atmospheric model to analyze how angular momentum transport and atmospheric waves influence circulation and heat distribution on tidally locked hot Jupiter planets, revealing mechanisms for jet formation and multiple steady states.

Contribution

It identifies the coupling between semi-diurnal tides and mean circulation as key to jet formation and explores how rotation period affects atmospheric dynamics and steady states.

Findings

Semi-diurnal tide couples with mean circulation to produce low-latitude jets.

Atmospheric indirect cells may form at low latitudes due to stellar irradiation.

Multiple steady states can exist for the same planetary parameters.

Abstract

The atmospheric circulation in the upper atmosphere of hot Jupiter planets is strongly influenced by the incoming stellar radiation. In this work we explore the results from a 3D atmospheric model and revisit the main processes driving the circulation in hot Jupiter planets. We use the angular momentum transport as a diagnostic and carry out a Fourier analysis to identify the atmospheric waves involved. We find that the coupling between the angular momentum transported horizontally by the semi-diurnal tide and the mean circulation is the mechanism responsible for producing the strong jet at low latitudes. Our simulations indicate the possible formation of atmospheric indirect cells at low latitudes. The formation of these cells is induced by the presence of the semi-diurnal tide that is driven by the stellar irradiation. The tropical circulation has an important impact transporting heat and momentum from the upper towards the lower atmosphere. One of the consequences of this heat and momentum transport is a global increase of the temperature. We show that the initial conditions do not affect the output of the reference simulation. However, when the period of rotation of the planet was increased ($P_{rot} > 5$ Earth days), vertical transport by stationary waves became stronger, transient waves became non-negligible, and Coriolis influence less dominant, which allowed a steady state with a strong retrograde jet to be stable. We found that at least two statically steady state solutions exist for the same planet parameters.