# A Scaling for Atmospheric Heat Redistribution on Tidally-Locked Rocky Planets

## TL;DR

This paper introduces an analytical scaling theory to predict atmospheric heat redistribution on tidally-locked rocky exoplanets, aiding interpretation of observations and improving 1D climate models.

## Contribution

It presents a novel analytical scaling for heat redistribution based on planetary parameters, validated against GCM simulations, bridging theory and upcoming JWST observations.

## Key findings

- Heat redistribution becomes significant above ~1 bar surface pressure.
- Thermal phase curves deviate from bare rock predictions with increasing pressure.
- The scaling applies to diverse atmospheres, including H2, CO, and lava worlds.

## Abstract

Atmospheric heat redistribution shapes the remote appearance of rocky exoplanets but there is currently no easy way to predict a planet's heat redistribution from its physical properties. This paper proposes an analytical scaling theory for the heat redistribution on tidally-locked rocky exoplanets. The main parameters of the scaling are a planet's equilibrium temperature, surface pressure, and broadband longwave optical thickness. The scaling compares favorably against idealized general circulation model simulations of TRAPPIST-1b, GJ1132b, and LHS 3844b. For these planets heat redistribution generally becomes efficient, and a planet's observable thermal phase curve and secondary eclipse start to deviate significantly from that of a bare rock, once surface pressure exceeds O(1) bar. The scaling additionally points to planetary scenarios for which heat transport can be notably more or less efficient, such as H2 and CO atmospheres or hot lava ocean worlds. The results thus bridge the gap between theory and imminent observations with the James Webb Space Telescope. They can also be used to parameterize the effect of 3D atmospheric dynamics in 1D models, thereby improving the self-consistency of such models.