Tidal dissipation in ice-covered, homogeneous-density oceans of variable thickness

Description

Tidal dissipation withinsubsurface oceans has been suggested as an important energy source in icymoons. However, previous studies are limited to subsurface oceans of constantthickness. Using the commercial finite element software Comsol Multiphysics, wedevelop a new model to study tides in oceans of changing thickness. We modelthe ocean using the Laplace Tidal Equations with a thickness dependent phasespeed and the overlying ice shell as a homogeneous elastic membrane. We usethis model to study the tidal response of an Enceladan ocean with meridionaldegree two and three ocean thickness variations. We observe that the responseof an ocean with degree two topography is given by the same modes as that of aconstant thickness ocean. For certain ocean thicknesses, resonances can occur;if this is the case tidal dissipation can be above Enceladus’ observedendogenic heat flux. When degree two topography is considered these resonancesoccur for oceans that are on average thicker. Rossby-Haurwitz waves, excited bythe obliquity tide, are less efficiently excited than in the constant thicknessocean case. Degree three topography mixes symmetric and antisymmetric modeswhich are otherwise only excited by the eccentricity and obliquity tide,respectively. While meridional ocean thickness variations change the oceanresponse, for ocean thicknesses in the range of those inferred from geodesytidal dissipation through this mechanism is still two or more orders of magnitudesmaller than Enceladus endogenic heat flux.

Period	13 Dec 2019
Event title	AGU Fall Meeting 2019
Event type	Conference
Location	San Francisco, United States
Degree of Recognition	International