PICASO 3.0: A One-Dimensional Climate Model for Giant Planets and Brown Dwarfs

TL;DR

PICASO 3.0 is a Python-based one-dimensional atmospheric model for giant planets and brown dwarfs, capable of simulating radiative-convective equilibrium and disequilibrium chemistry, aiding interpretation of upcoming JWST observations.

Contribution

The paper introduces an open-source, Python implementation of a 1D atmospheric model with new disequilibrium chemistry capabilities, building on a heritage Fortran code.

Findings

Model accurately simulates atmospheric states under various conditions.

Includes self-consistent disequilibrium chemistry treatment.

Widely applicable to hydrogen-dominated atmospheres.

Abstract

Upcoming James Webb Space Telescope (JWST) observations will allow us to study exoplanet and brown dwarf atmospheres in great detail. The physical interpretation of these upcoming high signal-to-noise observations requires precise atmospheric models of exoplanets and brown dwarfs. While several one-dimensional and three-dimensional atmospheric models have been developed in the past three decades, these models have often relied on simplified assumptions like chemical equilibrium and are also often not open-source, which limits their usage and development by the wider community. We present a python-based one-dimensional atmospheric radiative-convective equilibrium model. This model has heritage from the Fortran-based code (Marley et al.,1996} which has been widely used to model the atmospheres of Solar System objects, brown dwarfs, and exoplanets. In short, the basic capability of the original model is to compute the atmospheric state of the object under radiative-convective equilibrium given its effective or internal temperature, gravity, and host--star properties (if relevant). In the new model, which has been included within the well-utilized code-base PICASO, we have added these original features as well as the new capability of self-consistently treating disequilibrium chemistry. This code is widely applicable to Hydrogen-dominated atmospheres (e.g., brown dwarfs and giant planets).