Richard J.A.M. Stevens

Professor at the University of Twente

Wind energy · Turbulence · Environmental flows

Publication 107 · Ocean and geophysical convection

Toward understanding polar heat transport enhancement in subglacial oceans on icy moons

R. Hartmann, R.J.A.M. Stevens, D. Lohse, R. Verzicco, Geophys. Res. Lett. 51 (3) e2023GL105401 (2024).

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Main finding

At intermediate rotation, the simulations show enhanced polar heat transport but reduced low-latitude and global transport in the sampled no-slip spherical-convection DNS at Ra = 10^6. The scaling interpretations remain conditional, and application to icy moons is qualitative and quantitatively unvalidated.

Nusselt and boundary layer ratios against inverse Rossby number for a rotating spherical shell
How to read the figure. Heat transport in a rotating spherical shell against the inverse Rossby number, split between the polar region inside the tangent cylinder, the low latitudes, and the full sphere. The left column varies the radius ratio, the right the gravity profile. Rotation lifts the polar Nusselt number to about 1.27 times its non-rotating value while lowering it at low latitudes, and because the low latitudes carry most of the area the full sphere shows a net reduction. The lower panels give the polar-to-equatorial ratio and the thermal-to-viscous boundary layer thickness ratio. Relevance to icy moons remains qualitative. Open the full-resolution figure. Figure 3. R. Hartmann et al. (2024). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

Why rotation can redistribute heat toward poles without increasing the global total.

Research context

The spherical-shell calculation extends rotating-convection ideas from cylindrical cells to latitude-dependent geometry. Alignment of buoyancy and rotation permits Taylor-column and Ekman-pumping enhancement near the poles, whereas their near-orthogonal orientation suppresses radial transport at low latitude; salinity and planetary parameter values remain outside the simulated regime.

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