13 Dec 2022
13 Dec 2022
Status: this preprint is open for discussion.

Basal melt rates and ocean circulation under the Ryder Glacier ice tongue and their response to climate warming: a high resolution modelling study

Jonathan Wiskandt1,2, Inga Monika Koszalka1,2,3, and Johan Nilsson1,2 Jonathan Wiskandt et al.
  • 1Department of Meteorology, Stockholm University, Stockholm, Sweden
  • 2Bolin Centre for Climate Research, Stockholm, Sweden
  • 3Stockholm University Baltic Sea Centre, Stockholm, Sweden

Abstract. The oceanic forcing of basal melt under floating ice shelves in Greenland and Antarctica is one of the major sources of uncertainty in climate ice sheet modelling. We use a high resolution, non-hydrostatic configuration of the Massachusetts Institute of Technology general circulation model (MITgcm) to investigate basal melt rates and melt driven circulation in the Sherard Osborn Fjord under the floating tongue of Ryder Glacier, northwestern Greenland. The control model configuration, based on the first ever observational survey by Ryder 2019 Expedition, yielded melt rates consistent with independent satellite estimates. A protocol of model sensitivity experiments quantified the response to oceanic thermal forcing due to a warming Atlantic Water, and to the buoyancy input from the subglacial discharge of surface fresh water. We found that the average basal melt rates show a nonlinear response to oceanic forcing in the lower range of ocean temperatures, while the response becomes indistinguishable from linear for higher ocean temperatures, which unifies the results from previous modelling studies of other marine terminating glaciers. The melt rate response to subglacial discharge is sublinear, consistent with other studies. The melt rates and circulation below the ice tongue exhibit a spatial pattern that is determined by the ambient density stratification.

Jonathan Wiskandt et al.

Status: open (until 08 Feb 2023)

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Jonathan Wiskandt et al.

Jonathan Wiskandt et al.


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Short summary
Ice ocean interactions under floating ice tongues in Greenland and Antarctica is one of the major challenges in climate modelling and a source of uncertainty in future sea level projections. We use a high resolution ocean model to investigate basal melting and melt driven circulation under the floating tongue of Ryder Glacier, northwestern Greenland. We study the response to oceanic and atmospheric warming. Our results are universal and relevant for the development of climate models.