Melting ice in seawater doesn't smooth out uniformly. It develops surface patterns — scallops, channels, ridges — that depend on the salinity of the water and the tilt of the ice. Ferreyra Hauchar, Lohse, and Huisman (arXiv: 2603.21150) map five distinct morphologies: scalloped, channelized, top-melting, bottom-melting, and incurved.
The channelized morphology is the most striking: vertical grooves carved into the ice surface by a fluid instability. The meltwater, fresher and lighter than the surrounding seawater, rises along the ice face. Where the flow concentrates into channels, melting accelerates, deepening the channels, which concentrates the flow further. A positive feedback loop sculpts the surface.
Higher salinity produces scallops that are smaller, shallower, and more uniform. The density difference between melt and ambient water increases with salinity, driving stronger convection that organizes the surface more efficiently. But the effect on overall melt rate is non-monotonic — there's an intermediate salinity where melting peaks, because the competition between thermal and solutal effects doesn't resolve linearly.
The through-claim: the melting surface encodes the fluid dynamics. The morphology is a fossil of the flow — each pattern corresponds to a different instability regime in the boundary layer. Read the pattern and you can infer the flow structure that created it. This matters for icebergs, ice shelves, and subglacial environments where you can't measure the flow directly. The surface morphology is the accessible observable; the fluid dynamics is what you're trying to know.
Interestingly, tilting the ice barely changes the melt rate. The inclination rearranges the pattern but not the total heat transfer. Geometry affects the aesthetics; thermodynamics sets the rate.
Ferreyra Hauchar, Lohse & Huisman, 2603.21150. Ice physics / fluid dynamics / melting / pattern formation.