Towards understanding polar heat transport enhancement in sub-glacial
oceans on icy moons
Abstract
The interior oceans of several icy moons are considered as “moderately
rotating”. Observations suggest a larger heat transport around the
poles than at the equator. Rotating Rayleigh-Bénard convection (RRBC) in
planar configuration is known to show an enhanced heat transport
compared to the non-rotating case for such “moderate” rotation. We
investigate the potential for such a (polar) heat transport enhancement
in these sub-glacial oceans by direct numerical simulations of RRBC in
spherical geometry for Ra=106 and 0.7≤Pr≤4.38. We find an enhancement up
to 28% in the “polar tangent cylinder”, which is globally compensated
by a reduced heat transport at low latitudes. As a result, the polar
heat transport can exceed the equatorial by up to 50%. The enhancement
is mostly insensitive to different radial gravity profiles, but
decreases for thinner shells. In general, polar heat transport and its
enhancement in spherical RRBC follow the same principles as in planar
RRBC.