Effect of near‐terminus subglacial hydrology on tidewater glacier submarine melt rates

D. A. Slater,P. W. Nienow,D. N. Goldberg,T. R. Cowton,A. J. Sole

doi:10.1002/2014gl062494

D. A. Slater, P. W. Nienow + Show 3 more

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https://doi.org/10.1002/2014gl062494

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Abstract

AbstractSubmarine melting of Greenlandic tidewater glacier termini is proposed as a possible mechanism driving their recent thinning and retreat. We use a general circulation model, MITgcm, to simulate water circulation driven by subglacial discharge at the terminus of an idealized tidewater glacier. We vary the spatial distribution of subglacial discharge emerging at the grounding line of the glacier and examine the effect on submarine melt volume and distribution. We find that subglacial hydrology exerts an important control on submarine melting; under certain conditions a distributed system can induce a factor 5 more melt than a channelized system, with plumes from a single channel inducing melt over only a localized area. Subglacial hydrology also controls the spatial distribution of melt, which has the potential to control terminus morphology and calving style. Our results highlight the need to constrain near‐terminus subglacial hydrology at tidewater glaciers if we are to represent ocean forcing accurately.

Highlights

Observations of the mass balance of the Greenland ice sheet in recent decades have shown significant losses at the coastal margins [van den Broeke et al, 2009; Pritchard et al, 2009], much of which has been attributed to the thinning [Pritchard et al, 2009], speedup [Rignot and Kanagaratnam, 2006], and retreat [Jiskoot et al, 2012] of tidewater glaciers
Description of Experiments This study aims to determine the effect of variation in near-terminus subglacial hydrology on tidewater glacier submarine melt rates
A general circulation model, MITgcm, has been used to model near-ice water circulation and submarine melt rates driven by buoyant subglacial discharge at the terminus of an idealized tidewater glacier

Summary

Introduction

Observations of the mass balance of the Greenland ice sheet in recent decades have shown significant losses at the coastal margins [van den Broeke et al, 2009; Pritchard et al, 2009], much of which has been attributed to the thinning [Pritchard et al, 2009], speedup [Rignot and Kanagaratnam, 2006], and retreat [Jiskoot et al, 2012] of tidewater glaciers During this period, coastal waters were observed to warm [Holland et al, 2008; Christoffersen et al, 2011] with water from the Irminger current [Rignot et al, 2012], raising the possibility that Greenlandic tidewater glaciers reacted sensitively to ocean forcing. The effect of this distinction on tidewater glacier submarine melt rates remains largely unstudied and is the subject of this paper

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