  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.
