Multi-scale modelling of the ocean beneath ice shelves
Lead Research Organisation:
British Antarctic Survey
Department Name: Science Programmes
Abstract
See lead proposal.
Organisations
Publications
Kimura S
(2013)
Adaptation of an unstructured-mesh, finite-element ocean model to the simulation of ocean circulation beneath ice shelves
in Ocean Modelling
Jordan J
(2015)
On the Conditional Frazil Ice Instability in Seawater
in Journal of Physical Oceanography
Jordan J
(2014)
Modeling ice-ocean interaction in ice-shelf crevasses
in Journal of Geophysical Research: Oceans
Jenkins A
(2014)
The Effect of Meltwater Plumes on the Melting of a Vertical Glacier Face
in Journal of Physical Oceanography
Dinniman M
(2016)
Modeling Ice Shelf/Ocean Interaction in Antarctica: A Review
in Oceanography
| Description | Ocean circulation beneath the floating ice shelves of Antarctica is a key process that must be incorporated into coupled climate models if those models are to be used to project the future evolution of the ice sheet and its impact on global sea levels. We have taken a major step towards this goal by incorporating ice shelf processes into Fluidity-ICOM, a next-generation ocean circulation model. An important capability of this finite element model is its capacity to utilize meshes that are unstructured and adaptive in three dimensions. This geometric flexibility offers several advantages over previous modelling approaches. The model represents melting and freezing on all ice-shelf surfaces including vertical faces, treats the ice shelf topography as continuous rather than stepped, and does not require any smoothing of the ice topography or any additional parameterisations of the ocean mixed layer commonly used in other models. The model can also represent a water column that decreases to zero thickness at the 'grounding line', where the floating ice shelf is joined to its tributary ice streams that are fully grounded on the seabed. The model has first been applied to idealised ice-shelf geometries in order to demonstrate these capabilities. In these simple experiments, arbitrarily coarsening the mesh outside the ice-shelf cavity has little effect on the ice-shelf melt rate, while the mesh resolution within the cavity is found to be highly influential. Smoothing the vertical ice front increases the ice-covered area, allowing greater exchange with the ocean than in simulations with a realistic ice front. A vanishing water-column thickness at the grounding line has little effect in the simulations studied. We have also investigated the response of ice shelf basal melting to variations in deep water temperature in the presence of salt stratification. Following on from these investigations of idealised domains we have applied the model to a domain that represents Pine Island Glacier with boundaries that conform to real bathymetry and basal shelf topography. This ice shelf cavity presents a considerable challenge to any model, as it has strong buoyancy forcing from rapid melt, complex geometry due to a large submarine ridge, and a convoluted ice base deeply incised with narrow crevasses. |
| Sectors | Environment |