Skip to main content Accessibility help
×
Home

Numerical investigation of the effects of temporal variations in basal lubrication on englacial strain-rate distribution

  • Shin Sugiyama (a1), G. Hilmar Gudmundsson (a2) and Jakob Helbing (a3)

Abstract

The effects of spatial and temporal variations in basal lubrication on the englacial strain rate and surface velocity distribution are investigated with a numerical ice-flow model. General aspects of the solutions are compared to measurements made on Lauteraargletscher, Switzerland, in 2001, that showed diurnal fluctuations in both surface velocity and englacial vertical strain. We find that spatial gradients in basal lubrication can set up variations in the deviatoric stress field that increases with distance to the bed and has a maximum value near the glacier surface. This stress field produces a significant strain rate near the surface. The temporal evolution of a slippery zone is identified as a possible cause of the observed diurnal variations in the vertical strain rate. Although general aspects of the measurements can be explained in this way, the calculated vertical strain rates are too small, suggesting that the modeled effective viscosity values using Glen’s flow law are too large near the surface.

  • View HTML
    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Numerical investigation of the effects of temporal variations in basal lubrication on englacial strain-rate distribution
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Numerical investigation of the effects of temporal variations in basal lubrication on englacial strain-rate distribution
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Numerical investigation of the effects of temporal variations in basal lubrication on englacial strain-rate distribution
      Available formats
      ×

Copyright

References

Hide All
Balise, M. J. and C. F. Raymond. 1985. Transfer of basal sliding variations to the surface of a linearly viscous glacier. J. Glaciol., 31(109), 308–318.
Bauder, A. 2001. Bestimmung der Massenbilanz von Gletschern mit Fernerkundungsmethoden und Fliessmodellierungen: eine Sensitivitatsstudie auf dem Unteraargletscher. Eidg. Tech. Hochschule, Zürich. Versuchsanst. Wasserbau, Hydrol. Glaziol. Mitt. 169.
Blatter, H., Clarke, G. K. C. and Colinge, J. 1998. Stress and velocity fields in glaciers: Part II. Sliding and basal stress distribution. J. Glaciol., 44(148), 457–466.
Funk, M., Gudmundsson, G. H. and Hermann, F. 1995. Geometry of the glacier bed of the Unteraarglacier, Bernese Alps, Switzerland. Z. Gletscherkd. Glazialgeol., 30, 1994, 187–194.
Gudmundsson, G. H. 1999. A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland. J. Glaciol., 45(150), 219–230.
Hutter, K. 1983. Theoretical glaciology; material science of ice and the mechanics glaciers and ice sheets. Dordrecht, etc., D. Reidel Publishing Co.; Tokyo, Terra Scientific Publishing Co.
Iken, A. and Bindschadler, R. A. 1986. Combined measurements of sub-glacial water pressure and surface velocity of Findelengletscher, Switzerland: conclusions about drainage system and sliding mechanism. J. Glaciol., 32(110), 101–119.
Iken, A., Röthlisberger, H., Flotron, A. and Haeberli, W. 1983. The uplift of Unteraargletscherat the beginning of the melt season—a consequence of water storage at the bed? J. Glaciol., 29(101), 28–47.
Jansson, P. 1995. Water pressure and basal sliding on Storglaciaren, northern Sweden. J. Glaciol., 41(138), 232–240.
Kamb, B. and Engelhardt, H. 1987. Wavesof accelerated motion in a glacier approaching surge: the mini-surges of Variegated Glacier, Alaska, U.S.A. J. Glaciol., 33(113), 27–46.
Nye, J. F. 1965. The flow of a glacier in a channel of rectangular, elliptic or parabolic cross-section. J. Glaciol., 5(41), 661–690.
Raymond, C. F. and Malone, S. 1986. Propagating strain anomalies during mini-surges of Variegated Glacier, Alaska, U.S.A. J. Glaciol., 32(111), 178–191.
Sugiyama, S. and Gudmundsson, G. H. 2003. Diurnal variations in vertical strain observed in a temperate valley glacier. Geophys. Res. Lett., 30(2), 1090. (10.1029/2002GL016160.)
Vieli, A., Funk, M. and Blatter, H. 2000. Tidewater glaciers: frontal flow acceleration and basal sliding. Ann. Glaciol., 31, 217–221.
Vonmoos, M. 1999. Auswirkungenbasaler Storungen auf das Geschwindigkeitsfeld und die Oberflache eines Gletschers. (Diplomarbeit, Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie, ETH, Zurich.)
Willis, I. C. 1995. Intra-annual variations in glacier motion: a review. Prog. Phys. Geogr., 19(1), 61–106.
Zienkiewicz, O. C. 1977. The finite element method. Third edition. London, etc., McGraw-Hill Book Co.

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed