Europa's ocean translates interior tidal heating patterns to the ice-ocean boundary

TL;DR

This study uses numerical simulations to show how heterogeneous tidal heating in Europa's interior influences ocean circulation and ice shell thickness, highlighting the transfer of heating patterns from the seafloor to the ice shell.

Contribution

It demonstrates how mantle tidal heating patterns are transmitted to the ice shell via ocean convection, revealing their impact on ice thickness variations.

Findings

Polar regions have higher oceanic heat flux due to tidal heating.

Boundary-driven thermal winds transfer longitudinal heating variations.

Ocean control on ice thickness is significant when tidal heating dominates in the mantle.

Abstract

The circulation in Europa's ocean determines the degree of thermal, mechanical and chemical coupling between the ice shell and the silicate mantle. Using global direct numerical simulations, we investigate the effect of heterogeneous tidal heating in the silicate mantle on rotating thermal convection in the ocean and its consequences on ice shell thickness. Under the assumption of no salinity or ocean-ice shell feedbacks, we show that convection largely transposes the latitudinal variations of tidal heating from the seafloor to the ice, leading to a higher oceanic heat flux in polar regions. Longitudinal variations are efficiently transferred when boundary-driven thermal winds develop, but are reduced in the presence of strong zonal flows and may vanish in planetary regimes. If spatially homogeneous radiogenic heating is dominant in the silicate mantle, the ocean's contribution to ice shell thickness variations is negligible compared to tidal heating within the ice. If tidal heating is instead dominant in the mantle, the situation is reversed and the ocean controls the pole-to-equator thickness contrast, as well as possible longitudinal variations.