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.