Abstract
The connections between Greenland’s tidewater glaciers and the
continental shelf waters are modulated by fjords that are geometrically
complex with numerous modes of variability. These fjords transport heat
towards the glaciers and meltwater away, with a renewal determined by a
range of factors including buoyancy forcing at the surface (surface
melt) and at depth (subglacial discharge), wind stresses, shelf
currents, bathymetry, and mixing processes. This study aims to classify
the various regimes of flow and fjord renewal over the diverse parameter
space of Greenland fjords with an emphasis on investigating the role of
shelf-driven variability and mixing. We conduct idealized numerical
simulations using MITgcm to explore how fjord renewal is controlled by
elements of the shelf and fjord geometry, and by thermodynamic and
mechanical forcings, with domains consisting of idealized bays and
shelves representative of Greenland. Specifically, we investigate the
sensitivity of the renewal to the following dynamic/thermodynamic
influences: (a) bathymetric sills and their influence on mixing, (b)
horizontal constrictions (peninsulas, islands, turns), (c) ice cover,
and (d) subglacial meltwater discharge. To explain our numerical model
results, we develop dynamical theories for the exchange flow as a
function of the geometric and forcing parameters.