The Inhomogeneity Effect III: Weather Impacts on the Heat Flow of Hot Jupiters

TL;DR

This paper uses advanced 3D atmospheric models to show how weather and opacity inhomogeneities significantly influence heat flow and cooling in hot Jupiters, impacting their inflation and evolution.

Contribution

It demonstrates the critical role of atmospheric inhomogeneity effects in hot Jupiter heat transport, confirmed through coupled 3D models and analytical arguments.

Findings

Opacity inhomogeneity amplifies heat flux in hot Jupiters.

Atmospheric drag and temperature critically affect interior cooling.

3D models reveal larger cooling effects than 1D models.

Abstract

The interior flux of a giant planet impacts atmospheric motion, and the atmosphere dictates the interior's cooling. Here we use a non-hydrostatic general circulation model (Simulating Nonhydrostatic Atmospheres on Planets, SNAP) coupled with a multi-stream multi-scattering radiative module (High-performance Atmospheric Radiation Package, HARP) to simulate the weather impacts on the heat flow of hot Jupiters. We found that the vertical heat flux is primarily transported by convection in the lower atmosphere and regulated by dynamics and radiation in the overlying ``radiation-circulation" zone. The temperature inversion occurs on the dayside and reduces the upward radiative flux. The atmospheric dynamics relay the vertical heat transport until the radiation becomes efficient in the upper atmosphere. The cooling flux increases with atmospheric drag due to increased day-night contrast and spatial inhomogeneity. The temperature dependence of the infrared opacity greatly amplifies the opacity inhomogeneity. Although atmospheric circulation could transport heat downward in a narrow region above the radiative-convective boundary, the opacity inhomogeneity effect overcomes the dynamical effect and leads to a larger overall interior cooling than the local simulations with the same interior entropy and stellar flux. The enhancement depends critically on the equilibrium temperature, drag, and atmospheric opacity. In a strong-drag atmosphere hotter than 1600 K, a significant inhomogeneity effect in three-dimensional (3D) models can boost interior cooling several-fold compared to the 1D radiative-convective equilibrium models. This study confirms the analytical argument of the inhomogeneity effect in Zhang (2023a,b). It highlights the importance of using 3D atmospheric models in understanding the inflation mechanisms of hot Jupiters and giant planet evolution in general.