Articles | Volume 8, issue 4
The Cryosphere, 8, 1457–1468, 2014
The Cryosphere, 8, 1457–1468, 2014

Research article 08 Aug 2014

Research article | 08 Aug 2014

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

N. Chauché1, A. Hubbard1, J.-C. Gascard2, J. E. Box3,4, R. Bates5, M. Koppes6, A. Sole7, P. Christoffersen8, and H. Patton1 N. Chauché et al.
  • 1Department of Geography and Earth Science, Aberystwyth University, Aberystwyth, UK
  • 2Laboratoroire d'Océanographie et du Climat, Expérimentation et approche Numérique, Université Pierre et Marie Curie, Paris, France
  • 3Byrd Polar Research Center, The Ohio State University, Columbus, Ohio, USA
  • 4Geological Survey of Denmark and Greenland, Copenhagen, Denmark
  • 5School of Geography and Geosciences, St-Andrews University, St-Andrews, UK
  • 6Department of Geography, University of British Columbia, Vancouver, Canada
  • 7Department of Geography, University of Sheffield, Sheffield, UK
  • 8Scott Polar Research Institute, University of Cambridge, Cambridge, UK

Abstract. Warm, subtropical-originating Atlantic water (AW) has been identified as a primary driver of mass loss across the marine sectors of the Greenland Ice Sheet (GrIS), yet the specific processes by which this water mass interacts with and erodes the calving front of tidewater glaciers is frequently modelled and much speculated upon but remains largely unobserved. We present a suite of fjord salinity, temperature, turbidity versus depth casts along with glacial runoff estimation from Rink and Store glaciers, two major marine outlets draining the western sector of the GrIS during 2009 and 2010. We characterise the main water bodies present and interpret their interaction with their respective calving fronts. We identify two distinct processes of ice–ocean interaction which have distinct spatial and temporal footprints: (1) homogenous free convective melting which occurs across the calving front where AW is in direct contact with the ice mass, and (2) localised upwelling-driven melt by turbulent subglacial runoff mixing with fjord water which occurs at distinct injection points across the calving front. Throughout the study, AW at 2.8 ± 0.2 °C was consistently observed in contact with both glaciers below 450 m depth, yielding homogenous, free convective submarine melting up to ~200 m depth. Above this bottom layer, multiple interactions are identified, primarily controlled by the rate of subglacial fresh-water discharge which results in localised and discrete upwelling plumes. In the record melt year of 2010, the Store Glacier calving face was dominated by these runoff-driven plumes which led to a highly crenulated frontal geometry characterised by large embayments at the subglacial portals separated by headlands which are dominated by calving. Rink Glacier, which is significantly deeper than Store has a larger proportion of its submerged calving face exposed to AW, which results in a uniform, relatively flat overall frontal geometry.