3D radiative-transfer for exoplanet atmospheres. gCMCRT: a GPU accelerated MCRT code

TL;DR

gCMCRT is an open-source GPU-accelerated Monte Carlo radiative transfer code designed for fast, accurate 3D atmospheric modeling of exoplanets, capable of processing large GCM datasets and generating synthetic spectra.

Contribution

This work introduces gCMCRT, a novel GPU-accelerated Monte Carlo radiative transfer code that automates post-processing of 3D exoplanet atmosphere models for spectral analysis.

Findings

Supports multiple spectral modes including albedo, emission, and transmission.

Compatible with various high-resolution opacity tables and Doppler shifts.

Successfully post-processed GCM outputs from multiple research groups.

Abstract

Radiative-transfer (RT) is a key component for investigating atmospheres of planetary bodies. With the 3D nature of exoplanet atmospheres being important in giving rise to their observable properties, accurate and fast 3D methods are required to be developed to meet future multi-dimensional and temporal data sets. We develop an open source GPU RT code, gCMCRT, a Monte Carlo RT forward model for general use in planetary atmosphere RT problems. We aim to automate the post-processing pipeline, starting from direct global circulation model (GCM) output to synthetic spectra. We develop albedo, emission and transmission spectra modes for 3D and 1D input structures. We include capability to use correlated-k and high-resolution opacity tables, the latter of which can be Doppler shifted inside the model. We post-process results from several GCM groups including ExoRad, SPARC/MITgcm THOR, UK Met Office UM, Exo-FMS and the Rauscher model. Users can therefore take advantage of desktop and HPC GPU computing solutions. gCMCRT is well suited for post-processing large GCM model grids produced by members of the community and for high-resolution 3D investigations.