Short-term velocity and water-pressure variations down-glacier from a riegel, Storglaciären, Sweden
Open Access
- 1 January 1998
- journal article
- research article
- Published by Cambridge University Press (CUP) in Journal of Glaciology
- Vol. 44 (147), 359-367
- https://doi.org/10.1017/s0022143000002689
Abstract
During the 1991 94 summer held seasons, time-correlated measure-merits of water pressure and surface speed were made over and down-glacier from a major riegel on Storglaciären, Sweden. Measurements were made at sub-hourly time-scales in order to discern details in the diurnal cycle. Large water-input events, typically associated with rain storms, produced coherent, lagged surface-velocity responses that could be understood in terms of till deformation or decoupling, and these have been discussed elsewhere. The consequences of smaller diurnal water-pressure events w ere more enigmatic, in that acceleration of ice flow generally preceded the onset of the local water-pressure rise. From consideration of these data and other work done on the hydrology of Storglaciären, we infer that the ice in this area is generally pushed from behind via a relaxation in extensional strain across the riegel. Hence, accelerations occur in response to increases in water pressure that occur up-glacier and that precede local water-pressure rises. In addition, following a period of large storm events, surface speeds became more spatially coherent and were in phase with the diurnal water-pressure cycle. This suggests that the large water-pressure events lead to a spatially more homogeneous subglacial drainage system. Sliding laws need to take into account such temporal changes in spatial coherence of the subglacial drainage system.Keywords
This publication has 24 references indexed in Scilit:
- Flow Mechanism of Glaciers on Soft BedsScience, 1995
- Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier: 1. ObservationsJournal of Geophysical Research, 1994
- Instruments and Methods: Direct measurement of sliding at the glacier bedJournal of Glaciology, 1994
- Analysis of time series of glacier speed: Columbia Glacier, AlaskaJournal of Geophysical Research, 1987
- Waves of Accelerated Motion in a Glacier Approaching Surge: the Mini-Surges of Variegated Glacier, Alaska, U.S.A.Journal of Glaciology, 1987
- Combined measurements of Subglacial Water Pressure and Surface Velocity of Findelengletscher, Switzerland: Conclusions about Drainage System and Sliding MechanismJournal of Glaciology, 1986
- The Uplift of Unteraargletscher at the Beginning of the Melt Season—A Consequence of Water Storage at the Bed?Journal of Glaciology, 1983
- The Effect of the Subglacial Water Pressure on the Sliding Velocity of a Glacier in an Idealized Numerical ModelJournal of Glaciology, 1981
- Variations in the Sliding of a Temperate GlacierJournal of Glaciology, 1974
- On the Sliding of GlaciersJournal of Glaciology, 1957