Earth, With a Twist: How Orbital Parameters Affect the Photochemistry and Climate of Earth-like Exoplanet Atmospheres with ROCKE-3D

The interpretation of future observations of habitable exoplanets will depend critically on our understanding of how spectrally active gases are generated, maintained, and destroyed by photochemical reactions, transported throughout the atmosphere, and ultimately expressed in the disk-integrated spectrum. However, exoplanets are expected to have orbital parameters that differ from those of modern Earth, which will drive changes in both chemistry and climate. Studies of the impact on and by photochemistry with 3D models have begun exploring this parameter space (e.g., Chen et al., 2019; Braam et al., 2025), demonstrating that changes in orbital parameters and bulk atmospheric composition of essentially Earth-twin exoplanets could affect the abundances, distributions, and detectability of key biosignature gases like ozone (O3) and methane (CH4).