loading page

The impact of ice base topography, basal channels and subglacial discharge on basal melting — an exemplary numerical study for the floating ice tongue of the 79◦ North Glacier
  • +3
  • Mahdi Mohammadi Aragh,
  • Knut Klingbeil,
  • Ole Zeising,
  • Angelika Humbert,
  • Ralph Timmermann,
  • Hans Burchard
Mahdi Mohammadi Aragh
Leibniz Institute for Baltic Sea Research Warnemünde

Corresponding Author:[email protected]

Author Profile
Knut Klingbeil
Leibniz Institute for Baltic Sea Research Warnemuende (IOW)
Author Profile
Ole Zeising
Alfred-Wegener-Institut
Author Profile
Angelika Humbert
Alfred Wegner Institute Helmholtz Centre for Polar and Marine Science
Author Profile
Ralph Timmermann
Alfred Wegener Institute
Author Profile
Hans Burchard
Leibniz Institiute for Baltic Sea Research Warnemünde
Author Profile

Abstract

Realistically approximating the basal melting of ice shelves is critical for reliable climate model projections and the process representations in ice-ocean interaction. In this regard, extensive research attributes the massive thinning of vulnerable ice shelves to basal melting enhancement driven by ocean water warming, focusing mainly on oceanic warm water intrusion into the sub-shelf basins. However, climate models mainly underestimated the impacts of probable small-scale processes at the ice-ocean interface on basal melting by using smooth ice base topographies. This paper provides new insights into how small-scale features on the ice-ocean interface contribute to basal melting enhancement and spatial distribution. We developed a time-dependent, two-dimensional ice-shelf plume model as an optimal tool that allows a high-resolution representation of basal topography and with the unique ability to provide valuable information from the mixed boundary layer between ocean and ice shelves. In an exemplary case study for the floating ice tongue of the 79◦ North Glacier, systematic sensitive analyses were performed with the developed model. Our results show that the sub-km-scale basal channels with realistic dimensions increase the mean basal melt rate and generate extreme and sizeable lateral variability of melting at the grounding line. This mechanism is not reproducible with the tuning of drag coefficient. Besides, it reveals that the subglacial discharge in the channels has contradicting effects of reducing the melt rate by refreshing the sea water and increasing the freezing point while increasing the melt rate due to high water speed. However, the latter was dominant in our experiments.