Icy Worlds

Energetics Govern Ocean Circulation On Icy Ocean Worlds

By Keith Cowing
astro-ph.EP
June 2, 2022
Filed under
Energetics Govern Ocean Circulation On Icy Ocean Worlds
Energy dissipation rate per unit volume for thermally-driven flows predicted by the scaling in Eq. (26) as a function of the bottom heat flux (Q) times α/(ρcp) and the gravitational acceleration (g). The white stars mark the estimates for Snowball Earth (Ea), Europa (Eu) and Enceladus (En), assuming the parameters given in table 1. The colorbar is logarithmic with the contour interval a factor of √10.

Globally ice-covered oceans have been found on multiple moons in the solar system and may also have been a feature of Earth’s past. However, relatively little is understood about the dynamics of these ice-covered oceans, which affect not only the physical environment but also any potential life and its detectability.

A number of studies have simulated the circulation of icy-world oceans, but have come to widely different conclusions. To better understand and narrow down these diverging results, we discuss energetic constraints for the circulation on ice-covered oceans, focusing in particular on Snowball Earth, Europa, and Enceladus. Energy input that can drive ocean circulation on ice-covered bodies can be associated with heat and salt fluxes at the boundaries as well as ocean tides and librations.

We show that heating from the solid core balanced by heat loss through the ice sheet can drive an ocean circulation, but the resulting flows would be relatively weak and strongly affected by rotation. Salt fluxes associated with freezing and melting at the ice sheet boundary are unlikely to energetically drive a circulation, although they can shape the large-scale circulation when combined with turbulent mixing.

Ocean tides and librations may provide an energy source for such turbulence, but their strength remains highly uncertain for the icy moons, which poses a major obstacle to predicting the ocean dynamics of icy worlds and remains as an important topic for future research.

Malte F. Jansen, Wanying Kang, Edwin Kite

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2206.00732 [astro-ph.EP] (or arXiv:2206.00732v1 [astro-ph.EP] for this version)
Submission history
From: Malte Jansen
[v1] Wed, 1 Jun 2022 19:46:20 UTC (2,080 KB)
https://arxiv.org/abs/2206.00732
Astrobiology,

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