Seasonal control of Petermann Gletscher ice-shelf melt by the ocean’s response to sea-ice cover in Nares Strait
Date
2017-02-02
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Cambridge University Press
Abstract
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.
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SHROYER, E., PADMAN, L., SAMELSON, R., MÜNCHOW, A., & STEARNS, L. (2017). Seasonal control of Petermann Gletscher ice-shelf melt by the ocean's response to sea-ice cover in Nares Strait. Journal of Glaciology, 63(238), 324-330. doi:10.1017/jog.2016.140