Ocean and Sea Ice and their Interactions around Greenland and the West Antarctic Peninsula in Forced Fine-Resolution Global Simulations

Ablation along the margin of the Greenland ice sheet is accelerating, resulting in increasing contributions to global sea-level rise. Ice shelves overlay some 50% of the Antarctic continental margins where basal melt rates, mass loss, and grounding line retreat of ice shelves are also increasing. Ocean warming is implicated in both locations, however much is still not understood about the variability and changes over past decades in the composition and delivery pathways of water masses into the vicinity of the Greenland fjords and Antarctic ice cavities where land ice/ocean interactions take place. Our overall objective is to use a series of forced global eddying and eddy-resolving numerical simulations to investigate how the interplay of regional processes and decadal changes in local and remote forcing impact both these pathways and end member water mass compositions over the continental shelves of Greenland and Antarctica. We seek to understand delivery to the seaward limits of where ice shelves occur in reality in Antarctica and to the mouths of the Greenland fjords.

We propose to use two global coupled ocean and sea-ice models in this study: the Los Alamos National Laboratory Parallel Ocean Program (POP) and the Hybrid Coordinate Ocean Model (HYCOM), each coupled to the Los Alamos National Laboratory sea ice model (CICE) and run in the Community Earth System Model (CESM) framework. The importance of mesoscale stirring and advection and the value of using a hybrid vertical coordinate particularly over the continental shelf and slope will be investigated. The impact of atmospheric forcing that resolves katabatic winds and winter storms will be addressed using a final short POP/CICE simulation. Glacier melt will be represented by a spatially varying enhanced freshwater flux term as active land ice/ocean coupling is not yet available in CESM.

Our study will provide an understanding of the causes of regional change and variability along the continental margins of Greenland and Antarctica in a global and multi-decadal context where large-scale climate model teleconnections are present, as well as important small mesoscale processes that are likely key to the realistic representation of the continental shelf waters. Such high horizontal resolution in the study regions has not been used before in a global application. Our results will inform model developers as to the importance of using a hybrid vertical coordinate system and an eddy-resolving mesh in the vicinity of ocean/land-ice interaction sites in future climate models.