Preprints
https://doi.org/10.5194/egusphere-2022-1218
https://doi.org/10.5194/egusphere-2022-1218
 
07 Dec 2022
07 Dec 2022
Status: this preprint is open for discussion.

Hydraulic suppression of basal glacier melt in sill fjords

Johan Nilsson1,2, Eef van Dongen1,2, Martin Jakobsson3,2, Matt O'Regan3,2, and Christian Stranne3,2 Johan Nilsson et al.
  • 1Department of Meteorology, Stockholm University, 10691 Stockholm, Sweden
  • 2Bolin Center for Climate Research, Stockholm University, 10691 Stockholm, Sweden
  • 3Department of Geological Sciences, Stockholm University, 10691 Stockholm, Sweden

Abstract. Using a conceptual model, we examine how hydraulically-controlled exchange flows in silled fjords affect the relationship between the basal glacier melt and the features of warm intermediate Atlantic Water (AW) outside the fjords. We show that an exchange flow can be forced to transit into the hydraulic regime if the AW interface height decreases, the AW temperature increases, or the production of glacially modified water is boosted by subglacial discharge. In the hydraulic regime, the heat transport across the sill becomes a rate limiting factor for the basal melt, which is suppressed. An interplay between processes near the ice–ocean boundary and the hydraulically-controlled exchange flow determines the melt dynamics, and the sensitivity of the basal melt to changes of the AW temperature is reduced. The model results are discussed in relation to observations from Petermann, Ryder, and 79° N glaciers in North Greenland.

Johan Nilsson et al.

Status: open (until 06 Mar 2023)

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Johan Nilsson et al.

Johan Nilsson et al.

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Short summary
We investigate how topographical sills suppress basal glacier melt in Greenlandic fjords. The basal melt drives an exchange flow over the sill, but there is an upper flow limit set by the Atlantic Water features outside the fjord. If this limit is reached, the flow enters a new regime where the melt is suppressed and its sensitivity on the Atlantic Water temperature is reduced.