Turbulent heat exchange between water and ice at an evolving ice-water interface

TL;DR

This study experimentally investigates how turbulent water flow influences ice melting at an evolving ice-water interface, revealing that transient melting depends on flow strength and that ice reformation rate is independent of turbulence intensity.

Contribution

It provides a new experimental framework linking turbulent shear flow to ice melting dynamics and validates a one-dimensional model for basal melting rates.

Findings

Transient melting occurs at lower Reynolds numbers, complete melting at higher Reynolds numbers.

Ice reformation rate is independent of flow turbulence after melting episodes.

Model fits experimental data and explains basal melting rates of Antarctic ice shelves.

Abstract

We conduct laboratory experiments on the time evolution of an ice layer cooled from below and subjected to a turbulent shear flow of warm water from above. Our study is motivated by observations of warm water intrusion into the ocean cavity under Antarctic ice shelves, accelerating the melting of their basal surfaces. The strength of the applied turbulent shear flow in our experiments is represented in terms of its Reynolds number $\textit{Re}$, which is varied over the range $2.0\times10^3 \le \textit{Re} \le 1.0\times10^4$. Depending on the water temperature, partial transient melting of the ice occurs at the lower end of this range of $\textit{Re}$ and complete transient melting of the ice occurs at the higher end. Following these episodes of transient melting, the ice reforms at a rate that is independent of $\textit{Re}$. We fit our experimental measurements of ice thickness and temperature to a one-dimensional model for the evolution of the ice thickness in which the turbulent heat transfer is parameterized in terms of the friction velocity of the shear flow. The melting mechanism we investigate in our experiments can easily account for the basal melting rate of Pine Island Glacier ice shelf inferred from observations.