3/31/2023 0 Comments Rayleigh shellto![]() Potentially this behavior of the ice shell has important consequences for resurfacing and tectonic processes on Europa. I carefully determine the conditions under which this can occur. I show that modest variations in heat flux can force the system to switch between these two states, with consequent rapid changes in the ice shell thickness of 10-20 km. The implication fo this jump is that, for a range of heat fluxes, two ice-shell equilibria exist for a given heat flux, one comprising a thin, conductive shell and the other comprising a thick, convective shell. In contrast, a convective ice shell with low Rayleigh number, 10% change in flux involve changes of thickness large than 10 km.įor a convective fluid with temperature dependend vistosity, the heat flux jumps to a finite amplitude at the critical Rayleigh number. For example, for a conductive ice shell 3.5 km thick, a 10% change in basal heat flux causes a variation of the ice thickness of roughly 0.9 km. In contrast, for a conductive ice shell, large DeltaF involve relatively small deltah. I show that variations in heat flux, DeltaF, supplied to the base of a convective ice shell, cause large variations in the shell thickness, deltah. The numerical model considers a Newtonian rheology for the water ice. The Boussinesq fluid equations are solved using the ConMan finite-element code. ![]() Numerical experiments are performed to explore the behavior of a convective ice shell with strongly temperature-dependent viscosity both with and without internal heating. I investigate the response of the ice shell to changes of heat production in the interior of the satellite. The heat transfer from the silicate interior to the surface occurs in the ice shell by thermal conduction or possibly by stagnant lid convection. Variations in heat production may have been caused by changes in the satellite's orbit over time (timescales 10^8 yr), with episodic thermal activity on the sea floor. Europa could undergo gradual or rapid changes of heat production during its thermal history. ![]()
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