Seasonal control of Petermann Gletscher ice-shelf melt by the ocean's response to sea-ice cover in Nares Strait

• Published in: Journal of Glaciology
• Main Authors: E. L. SHROYER, L. PADMAN, R. M. SAMELSON, A. MÜNCHOW, L. A. STEARNS
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2017
• Subjects: basal melt ice shelf; landfast sea ice; Nares Strait; ocean/glacier interactions; ocean/ice interactions; Petermann Gletscher; sea-ice arching; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Greenland; Nares; Petermann Fjord; glacier; Ice Sheet; Ice Shelf; Journal of Glaciology; Nares strait; Petermann gletscher; Sea ice
• Online Access: https://doi.org/10.1017/jog.2016.140; https://doaj.org/article/3f250c0757094bcfb6bd6c2edfd065f4

Petermann Gletscher drains ~4% of the Greenland ice sheet (GrIS) area, with ~80% of its mass loss occurring by basal melting of its ice shelf. We use a high-resolution coupled ocean and sea-ice model with a thermodynamic glacial ice shelf to diagnose ocean-controlled seasonality in basal melting of the Petermann ice shelf. Basal melt rates increase by ~20% in summer due to a seasonal shift in ocean circulation within Nares Strait that is associated with the transition from landfast sea ice to mobile sea ice. Under landfast ice, cold near-surface waters are maintained on the eastern side of the strait and within Petermann Fjord, reducing basal melt and insulating the ice shelf. Under mobile sea ice, warm waters are upwelled on the eastern side of the strait and, mediated by local instabilities and eddies, enter Petermann Fjord, enhancing basal melt down to depths of 200 m. The transition between these states occurs rapidly, and seasonal changes within Nares Strait are conveyed into the fjord within the same season. These results suggest that long-term changes in the length of the landfast sea-ice season will substantially alter the structure of Petermann ice shelf and its contribution to GrIS mass loss.