The Role of Ocean Dynamics in Shaping Exoplanetary Climate and Habitability

Di Paolo, Maria (2026) The Role of Ocean Dynamics in Shaping Exoplanetary Climate and Habitability. Doctoral thesis, University of East Anglia.

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Abstract

Characterising terrestrial exoplanets requires physically consistent climate modelling, including ocean dynamics, often neglected despite its dominant role in shaping climate. This is especially relevant for planets orbiting low-mass stars, the primary targets for habitability studies, whose climatic complexity remains underexplored and for which oceans cannot be assumed to be Earth-like.

Tidal interactions can substantially modify ocean mixing and the heat-transport mechanisms operating on Earth-like aquaplanets. The climatic response to different tidal mixing, represented in a fully coupled atmosphere-ocean general circulation model through the vertical diffusion coefficient, is nonlinear and nonmonotonic: moderate diffusivities enhance ocean heat transport and reduce meridional temperature gradients, peaking at values about 100 times those of Earth, whereas stronger mixing reverses these effects. Consequently, certain tidal forcing regimes can widen the habitable zone by enabling temperate climates under reduced instellation, indicating that ocean tides are a key factor in assessing the habitability of planets affected by strong tidal forcing, such as planets orbiting low-mass stars.

In this context, the climate dynamics of terrestrial exoplanets in 3:2 spin-orbit resonances is examined, a configuration that remains understudied relative to synchronous rotation, characterised by fixed day and night hemispheres. Two tidal regimes and two rotation states are analysed, and simulations with both dynamic and thermodynamic oceans assess the role of ocean processes in climate and observability. Periodic stellar forcing shapes both mean climate and variability, producing migrating temperature and precipitation patterns. These result in distinctive thermal emission phase-curve signatures that differentiate asynchronous from synchronous rotators.

Overall, this thesis provides an assessment of terrestrial planets climates highlighting the importance of fully coupled ocean dynamics in shaping their climatic and observational properties. The findings contribute to clarifying the diversity of climates permitted by asynchronous rotation and offer a framework for interpreting future observations of nearby terrestrial exoplanets.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Engineering, Mathematics and Physics
Depositing User:	Chris White
Date Deposited:	04 Jun 2026 08:05
Last Modified:	04 Jun 2026 08:05
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103274
DOI:

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