Enceladus

The Role Of Ocean Circulation In Driving Hemispheric Symmetry Breaking Of The Ice Shell Of Enceladus

By Keith Cowing
astro-ph.EP
April 1, 2022
Filed under
The Role Of Ocean Circulation In Driving Hemispheric Symmetry Breaking Of The Ice Shell Of Enceladus
Schematics of ocean circulation and heat transport for the (a) shell-heating and (b) core-heating scenarios. Note that only the hemispherically-asymmetric patterns are shown. The upward-pointing curly red arrows show fluxes entering from the bottom and exiting at the top. The horizontally-directed curly red arrow shows the lateral heat transport by ocean circulation. The red shading in the ice shell mark the patterns of tidal heating which peak over the poles where the ice is thin, largest over the south pole. Broad patterns of melting and freezing are marked, together with the rate, along with the associated salinity anomalies. Melting and freezing are balanced by lateral ice transport within the ice shell, directed from thick to thin. Rates of melting (fast, slow) are based on consideration of Fig. 5b. The broad patterns of anomalous overturning circulation in the ocean are indicated by the thick curved arrows, which are color-coded to indicate the salt transport. Dark brown denotes the flow of dense salty water, light yellow that of buoyant fresh water. The water is coldest just under the thickest ice, which occurs at the equator. The water beneath is warmer, in part due to bottom heating. Water properties in different parts of the ocean are indicated by text boxes.

The ice shell of Enceladus exhibits strong asymmetry between its hemispheres, with all known geysers concentrated over the south pole, even though its orbital configuration is almost perfectly symmetric.

By exploring ocean circulation across a range of ocean salinities and core/shell heating partitions, we study the role of ice-ocean interaction in hemispheric symmetry breaking. We find that: (i) asymmetry is enhanced by cross-equatorial ocean heat transport when the ice shell is the major heat source and vice versa, (ii) the magnitude of ocean heat transport is comparable to the global heat production, significantly affecting the ice shell evolution and equilibrium state and (iii) more than one equilibrium state can exist due to a positive feedback between melting and ocean circulation.

Wanying Kang, Suyash Bire, John Marshall

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2203.16611 [astro-ph.EP] (or arXiv:2203.16611v1 [astro-ph.EP] for this version)
Submission history
From: Wanying Kang
[v1] Wed, 30 Mar 2022 18:47:57 UTC (2,725 KB)
https://arxiv.org/abs/2203.16611
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