Modelling the Interconnection of the Ocean and the Greenland Ice Sheet

• Author / Creator

  Gillard, Laura C.

• The Greenland Ice Sheet (GrIS) is the largest freshwater reservoir in the Northern Hemisphere and continues to discharge large amounts of meltwater and icebergs into the ocean. The ice sheet has the potential to raise the sea-level by over 7 metres and impact ocean circulations. Greenland’s marine-terminating glaciers (MtG) drain most of the ice sheet; therefore, ocean-induced undercutting of MtG has a strong control over the state of the ice sheet.

  The understanding of the interconnection between the ocean and the GrIS is limited. Knowledge of the processes that drive the renewal of warm water in the deep troughs along the Greenland shelf that connect to fjords with MtG has not been studied for the entirety of the coastline. The influence that the GrIS may have on large-scale ocean features, such as the Labrador Sea convection and the Atlantic Meridional Overturning Circulation (AMOC), is still not completely understood. Furthermore, when forcing an ocean general circulation model, it is not clear which freshwater estimates of the GrIS to use over another or how different estimates may influence ocean processes.

  Therefore, this thesis presents results from a suite of ocean model experiments, to investigate the complicated interactions between the ocean and the GrIS. This thesis first shows that the processes which drive the delivery of ocean heat respond differently by region to increasing GrIS meltwater, the origin of the warm water, how the water travels and is transformed, and local processes such as heat loss to the atmosphere. The Labrador Sea Water formation was impacted by a combination of altered lateral exchange from the shelf to the interior of the Labrador Sea as well as altered air-sea heat fluxes. An increase in vertical resolution, in the ocean model, generated unrealistic shallow mixed layer depths with a surface buoyancy cap that could not be broken. In order to break the buoyancy cap and generate a realistic mixed layer depth, a stronger heat loss was required at the surface of the ocean. Finally, based on a decade-long study period with an eddy-permitting ocean model, the GrIS meltwater and iceberg discharge did not have an impact on the Labrador Sea convection or the AMOC. However, ocean systems nearby the GrIS responded to varying freshwater flux estimates.

• Subjects / Keywords

  • Greenland Ice Sheet
  • Ocean Modelling
  • Labrador Sea
  • Iceberg
  • Atlantic water
  • Labrador Sea Water Formation

• Graduation date

  Spring 2021

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-p634-yg06

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.