Connect Store: A fully coupled 3D model of ice flow, calving, subglacial hydrology and ice-ocean interactions applied to Store Glacier, Greenland
This dissertation uses the 3D, finite-element, full-Stokes, open-source model Elmer/Ice to investigate the coupled dynamics of the ice-calving-subglacial-hydrology-plume system at Store Glacier, a large, fast-flowing tidewater outlet glacier on the west coast of Greenland. Understanding these large outlet glaciers is critical to being able to accurately predict the future evolution of the Greenland Ice Sheet. This study therefore presents a three-week record of calving activity at Store Glacier, gathered in July 2017 using a terrestrial radar interferometer. This record is the longest and most detailed yet produced for a Greenlandic tidewater glacier and shows the complex and time-varying nature of calving at Store Glacier. In parallel, an uncoupled model of subglacial hydrology and plume melting at the calving front is developed within the Elmer/Ice framework and applied to Store Glacier to investigate seasonal differences in hydrology. Overall, the dynamic nature and key role of the subglacial hydrological system of Store is made clear, with little modelled relationship between surface melt and plume melt, owing to the storage capacity of the intervening subglacial system. The model is compared to available observations, which suggest that it is providing a realistic picture of the subglacial hydrology of Store Glacier. Finally, a fully coupled model of ice flow, calving, subglacial hydrology and plume melting is presented and applied to Store Glacier, being validated against the observed calving dataset. This represents the first time a fully coupled simulation of a tidewater glacier anywhere has been undertaken. The model qualitatively reproduces the validation dataset well, but under-estimates it quantitatively. The coupled model allows demonstration of the dynamics of the coupled ice-hydrology-calving system, showing that hydrology-induced velocity changes are the key large-scale calving control, and that channelisation inland is greatly suppressed when two-way ice-hydrology coupling is included. It also makes clear that, while the terminus appears to be able to channelise fully under high melt, this is not the case farther inland, mirroring the situation observed in land-terminating regions of the Greenland Ice Sheet.