An Energy Balance Model for Rapidly and Synchronously Rotating Terrestrial Planets

TL;DR

This paper introduces HEXTOR, an advanced energy balance model for calculating temperature profiles on Earth and exoplanets, incorporating a lookup table method and a tidally locked coordinate system for better accuracy.

Contribution

The paper presents HEXTOR, a novel energy balance model with improved radiative transfer parameterization and a coordinate system for synchronous planets, validated against Earth and exoplanet cases.

Findings

HEXTOR accurately models Earth's temperature profiles.

The tidally locked coordinate system improves temperature predictions for synchronous exoplanets.

HEXTOR shows better agreement with general circulation models than previous latitudinal models.

Abstract

This paper describes the Habitable Energy balance model for eXoplaneT ObseRvations (HEXTOR), which is a model for calculating latitudinal temperature profiles on Earth and other rapidly rotating planets. HEXTOR includes a lookup table method for calculating the outgoing infrared radiative flux and planetary albedo, which provides improvements over other approaches at parameterizing radiative transfer in an energy balance model. Validation cases are presented for present-day Earth and other Earth-sized planets with aquaplanet and land planet conditions from 0 to 45 degrees obliquity. A tidally locked coordinate system is also implemented in the energy balance model, which enables calculation of the horizontal temperature profile for planets in synchronous rotation around low mass stars. This coordinate transformed model is applied to cases for TRAPPIST-1e as defined by the TRAPPIST Habitable Atmosphere Intercomparison protocol, which demonstrates better agreement with general circulation models compared to the latitudinal energy balance model. Advances in applying energy balance models to exoplanets can be made by using general circulation models as a benchmark for tuning as well as by conducting intercomparisions between energy balance models with different physical parameterizations.