Spatial and temporal variations in surface velocity and basal drag across the tongue of the polythermal glacier midre Lovenbreen, Svalbard

D. M. Rippin, I. C. Willis, N. S. Arnold, A. J. Hodson, M. Brinkhaus

Research output: Contribution to journalArticlepeer-review

Abstract

We present results of a detailed investigation of surface motion across the tongue of a polythermal glacier, midre Lovenbreen, Svalbard, during the 1999 summer. Surface velocities in the warm-based upper tongue increased during periods of enhanced surface melting and rainfall events, and force-balance analysis indicates that these velocity variations were locally forced, probably by fluctuations in subglacial water pressure. Surface speed-ups were also observed on the cold-based lower tongue (which acted as a sticky spot, through which there was minimal subglacial drainage for most of the summer), but these were largely non-locally forced by longitudinal coupling to the faster-moving ice up-glacier. On one occasion, however, a large, rapid input of surface water to the glacier reduced the basal drag beneath the cold-based lower tongue, presumably due to hydraulic jacking. This resulted in locally forced enhanced surface velocities across the entire tongue, accompanied by a breaching of the lower tongue and an outburst of subglacially stored water.

Original languageEnglish
Pages (from-to)588-600
Number of pages13
JournalJournal of Glaciology
Volume51
Issue number175
Publication statusPublished - 2005

Keywords

  • SUBGLACIAL WATER-PRESSURE
  • DRAINAGE SYSTEM
  • FORCE BUDGET
  • MASS-BALANCE
  • ICE SHEETS
  • SURGE-TYPE
  • MOTION
  • COLD
  • FLOW
  • SWITZERLAND

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