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

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 Non-hydrostatic Atmospheres on Planets) coupled with a multi-stream multi-scattering radiative module (High-performance Atmospheric Radiation Package) 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 the companion papers by Zhang. It highlights the importance of using 3D atmospheric models in understanding the inflation mechanisms of hot Jupiters and giant planet evolution in general.

The Inhomogeneity Effect. II. Rotational and Orbital States Impact Planetary Cooling

“…Limited by the analytical framework, we could not explore the 3D distribution of opacity on giant planets and their impact on the cooling flux in this study. In the next paper (Zhang et al 2023), we will use a non-hydrostatic general circulation model to examine the inhomogeneity effects of incident stellar flux and opacity, as well as that of atmospheric dynamics in a self-consistent fashion.…”

“…To provide a quantitative explanation for real-world data, a dynamical model of giant planets is required. In the next paper (Zhang et al 2023), we will present an example that investigates the impact of general circulation on heat transport in tidally locked exoplanets.…”

“…These areas, due to their steeper temperature gradients, permit a greater amount of internal heat flux to escape into space. In our next paper (Zhang et al 2023), we will extend the radiator fins analogy to include opacity inhomogeneity, thus illustrating the impact of temperature-dependent opacity on the interior cooling of tidally locked gas giants.…”

The Inhomogeneity Effect. I. Inhomogeneous Surface and Atmosphere Accelerate Planetary Cooling

“…In the next paper (Zhang 2023), we will examine the effects of rotational and orbital states on interior cooling. In our third paper in this series (Zhang et al 2023), we will conduct numerical simulations on tidally locked exoplanets to shed light on the heating and cooling mechanisms of hot Jupiters.…”

“…We will also examine how rotational and orbital configurations impact the global surface cooling of airless planets and the interior cooling of giant planets. In the third paper (Zhang et al 2023), we will specifically focus on tidally locked giant planets, using a non-hydrostatic general circulation model to explore how atmospheric inhomogeneity affects their interior cooling and our understanding of the heating mechanisms on these planets.…”