BedMachine v3: Complete Bed Topography and Ocean Bathymetry Mapping of Greenland From Multibeam Echo Sounding Combined With Mass Conservation.

Mathieu Morlighem ,Jan Erik Arndt ,Hélène Seroussi ,Alun Hubbard ,C Williams ,Nolwenn Chauché ,J Mouginot ,Boris Dorschel ,Colm Ó'cofaigh ,Martín J Siegert ,Kelly Hogan ,Julian A Dowdeswell ,Patricia Slabon ,Martin Jakobsson ,Eric Rignot ,Wilhelm Weinrebe ,Lu An ,Ian Fenty ,Michael Wood ,S J Palmer ,Thomas M Jordan ,Søren Rysgaard ,Romain Millan ,Kristian K Kjeldsen ,I M Howat ,Brice Nöel ,Jonathan Bamber ,M R Van Den Broeke ,Larry A Mayer ,G A Catania ,F Straneo ,Karl B Zinglersen

doi:10.1002/2017gl074954

Abstract

Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics, and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic water (AW) that rapidly melts and undercuts Greenland's marine‐terminating glaciers. Here we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation approach. A new 150 m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous data sets, particularly in the marine‐terminating sectors of northwest and southeast Greenland. Our map reveals that the total sea level potential of the Greenland ice sheet is 7.42 ± 0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine‐based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.

Highlights

Subglacial bed topography and seafloor bathymetry provide fundamental controls on ice dynamics and ocean circulation along Greenland’s periphery
We present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation approach
NASA’s Operation IceBridge (OIB) has tripled the amount of ice thickness data, by flying more than 580,000 km of flight tracks over Greenland (Rodriguez-Morales et al, 2014). These data, combined with other data and a mass conservation approach, have transformed our knowledge of the bed topography of the Greenland ice sheet (Morlighem et al, 2014a). Despite this wealth of data, bed topography remains challenging to map along the coastal margins because radar-derived ice thickness data of sufficient quality are lacking in the vicinity of calving fronts, and measurements of fjord bathymetry have often been scarce to nonexistent until recently

Summary

Introduction

Subglacial bed topography and seafloor bathymetry provide fundamental controls on ice dynamics and ocean circulation along Greenland’s periphery. We present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation approach.

Results

Conclusion