Albedos, Equilibrium Temperatures, and Surface Temperatures of Habitable Planets

TL;DR

This paper uses 3D climate models to predict how albedo and temperatures of habitable exoplanets vary with stellar flux and temperature, improving habitability assessments beyond simple equilibrium temperature estimates.

Contribution

It introduces a method to estimate albedo and surface temperature variability from external stellar parameters using climate simulations.

Findings

Albedo varies significantly among habitable planets.

Surface temperature can be accurately predicted from stellar flux and temperature.

Equilibrium temperature alone is insufficient for habitability assessment.

Abstract

The potential habitability of known exoplanets is often categorized by a nominal equilibrium temperature assuming a Bond albedo of either 0.3, similar to Earth, or 0. As an indicator of habitability, this leaves much to be desired, because albedo on other planets can be very different, and because surface temperature exceeds equilibrium temperature due to the atmospheric greenhouse effect. We use an ensemble of 3-dimensional general circulation model simulations to show that for a range of habitable planets, much of the variability of Bond albedo, equilibrium temperature, and even surface temperature can be predicted with useful accuracy from incident stellar flux and stellar temperature, two known external parameters for every confirmed exoplanet.