Linking Overturning, Recirculation, and Melt in Glacial Fjords
- Ken Zhao,
- Andrew Stewart,
- James C. McWilliams
Abstract
Fjord circulation modulates the connection between marine-terminating
glaciers and the ocean currents offshore. These fjords exhibit both
overturning and horizontal recirculations, which are driven by water
mass transformation at the head of the fjord via subglacial discharge
plumes and distributed meltwater plumes. However, little is known about
the interaction between the 3D fjord circulation and glacial melt and
how relevant fjord properties influence them. In this study,
high-resolution numerical simulations of idealized glacial fjords
demonstrate that recirculation strength controls melt, which feeds back
on overturning and recirculation. The overturning circulation strength
is well predicted by existed plume models for face-wide melt and
subglacial discharge, while relationships between the overturning,
recirculation, and melt rate are well predicted by vorticity balance,
reduced-order melt parameterizations, and empirical scaling arguments.
These theories allow improved predictions of fjord overturning,
recirculation, and glacial melt by taking intrafjord dynamics into
account.