EOS-ESTM: a flexible climate model for habitable exoplanets

Abstract

Rocky planets with temperate conditions provide the best chance for discovering habitable worlds and life outside the Solar System. In the last decades, new instrumental facilities and large observational campaigns have been driven by the quest for habitable worlds. Climate models aimed at studying the habitability of rocky planets are essential tools to pay off these technological and observational endeavours. In this context, we present EOS-ESTM, a fast and flexible model aimed at exploring the impact on habitability of multiple climate factors, including those unconstrained by observations. EOS-ESTM is built on ESTM, a seasonal-latitudinal energy balance model featuring an advanced treatment of the meridional and vertical transport. The novel features of EOS-ESTM include: (1) parameterizations for simulating the climate impact of oceans, land, ice, and clouds as a function of temperature and stellar zenith distance; (2) a procedure (EOS) for calculating the radiative transfer in atmospheres with terrestrial and non-terrestrial compositions illuminated by solar- and non-solar-type stars. By feeding EOS-ESTM with Earth’s stellar, orbital and planetary parameters we derive a reference model that satisfies a large number of observational constraints of the Earth’s climate system. Validation tests of non-terrestrial conditions yield predictions that are in line with comparable results obtained with a hierarchy of climate models. The application of EOS-ESTM to planetary atmospheres in maximum greenhouse conditions demonstrates the possibility of tracking the snowball transition at the outer edge of the HZ for a variety of planetary parameters, paving the road for multi-parametric studies of the HZ.

Sporadic Spin-orbit Variations in Compact Multiplanet Systems and Their Influence on Exoplanet Climate

“…Relaxing these assumptions with an intermediate-complexity GCM is appropriate as our study is not designed to reproduce climate behaviors with high realism nor predict specific exo-atmospheric compositions but rather provide a more generally meaningful result. In addition, such GCMs with reduced complexity permit simulation of key 3D processes including cloud formation, large-scale circulation, moist processes, and climate feedback at a lower computational cost (see, e.g., Biasiotti et al 2022 for another category of computationally inexpensive but accurate climate models). This will become crucial when we need to compute a diverse range of anticipated exoplanet compositions.…”

Climate and atmospheric models of rocky planets: habitability and observational properties

“…Thanks to its extremely low computational cost, it can be used to explore the parameter space unconstrained by observations of individual rocky (exo)planets, or to perform statistical studies of climate properties whenever many runs for different parameter configurations are needed. The model has been recently upgraded and its most recent version, EOS-ESTM (Biasiotti et al 2022), includes a new code, EOS, (Simonetti et al 2022;Simonetti 2022) for the treatment of the radiative transfer, as well as a number of parametrizations to simulate the climate impact of oceans, land, ice, and clouds as a function of temperature and host star zenith distance. EOS-ESTM can be applied to a large variety of rocky planets, with terrestrial and non-terrestrial atmospheric compositions illuminated by solar-and nonsolar-type stars.…”

Functionality of Ice Line Latitudinal EBM Tenacity (FILLET). Protocol Version 1.0. A CUISINES Intercomparison Project

“…Annually averaged temperatures (left) and TOA albedos (right) as a function of latitude for Benchmarks 1 (black), 2 (red), and 3 (gold), as calculated by ESTM. The values of the parameters unspecified in this paper have either been taken from Biasiotti et al (2022;dashed lines) or tuned to produce an average global temperature of 288 K in Benchmark 1 (solid lines). Tuning has been achieved by lowering the cloud OLR forcing from 26.1 W m −2 (the average value for Earth; Pierrehumbert 2010) to 21.4 W m −2 .…”