Publication Date:
2024-02-21
Description:
Subsurface oceans rich in salts may be prevalent in the icy worlds of the outer solar system. Surface observations have led to various hypotheses for the transport of materials from the seafloor to the surface by hydrothermal plumes, and raise questions about heat transfer mechanisms. Chemical heterogeneity affects the vigor of convection, the forms of plumes, the generation and destruction of stratified or finger structures in the ocean, and thus the transport of heat and materials from the interior to the surface. Here, we investigate the layering phenomenon in a double‐diffusive convection system, which can occur when both the temperature and concentration influence the density of the fluid. The persistence of layers may depend on the buoyancy ratio, the Rayleigh number, boundary conditions, and initial conditions, which alter the chemical distribution and thus the balance between thermal and chemical buoyancies. Our simulations suggest that the layering could exist for a longer duration if the buoyancy ratio is raised with boundary conditions that maintain a large concentration difference. When the layers are present, heat and material transport are significantly inhibited through the subsurface ocean from the silicate interior to the base of the icy shell.
Description:
Plain Language Summary:
The subsurface oceans of icy satellites are almost certainly salt to some degree, and this gives rise to the possibility of layering by the process of double‐diffusive convection. The evolution of layers has long been a topic of interest for the terrestrial ocean, and under subsurface ocean conditions there are additional motives to study this phenomenon, as the layers can hinder heat and material transport and thus have to be taken into account when considering the evolution of the icy moons and what could be observed on the surface. We investigate the evolution of layers in a double‐diffusive convection system, where both the temperature and the concentration affect the density of the fluid. We examine the development of the first and subsequent layers, how they emerge and finally disappear, and what could prolong their lifetimes.
Description:
Key Points:
Layer formation is possible in a subsurface ocean that is heated from below, enriched in salts at the bottom and fresher on top.
Layering is a transient feature, but this can be long lasting if the concentration difference between the top and bottom is large.
As heat and material transport is inhibited while layers exist, the subsurface ocean may not be efficient in transport.
Description:
DFG
Description:
https://doi.org/10.35003/OIT7ZO
Keywords:
ddc:523
;
subsurface oceans
;
icy moons
;
layering
;
transport mechanism
Language:
English
Type:
doc-type:article
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