A wireless multi-sensor subglacial probe for investigating the deforming glacier bed

• Main Author: Rose, Kathryn Clare
• Format: Thesis
• Language: English
• Published: University of Southampton 2008
• Subjects: Norway; glacier
• Online Access: https://eprints.soton.ac.uk/466492/; https://eprints.soton.ac.uk/466492/1/1184107.pdf

The mechanisms that control glacier dynamics and fast ice stream flow are still poorly understood, largely due to the inaccessibility of the subglacial environment. One of the ways to improve on current investigations is to broaden the methods used to monitor the subglacial environment. An autonomous multi-sensor wireless probe was developed for use within an Environmental Sensor Network at Briksdalsbreen, Norway. Probes were deployed at the base of boreholes, measuring temperature, pressure, resistance (a proxy for conductivity), case strain, and tilt, six times a day. The probes used radio communications to transfer data to a base station at the glacier surface. The data was then sent to a reference station, which uploaded it onto the internet on a daily basis. In excess of a year's worth of data was obtained from several probes, deployed between 2004-2006. Readings of case strain and tilt indicated when the probes had become incorporated into the deforming bed. A reduction in sensor activity was displayed as the glacier changed from a summer to a winter regime. In the following spring, the sensors showed an increase in activity, particularly in water pressure. An Emergent Spring Event was recorded in February, followed by the actual Spring Event. This marked a transition to summer conditions within the glacier's hydrological system. Sliding was the dominant mechanism of basal motion during this time. In the summer, the probes began to rotate as the dominant form of basal motion transferred from sliding to till deformation. The movement of the probes was in keeping with the Taylor (1923) mechanism of clast rotation. Sedimentological analyses under the scanning electron microscope presented a relatively simple model for grain erosion within the deforming bed. Erosion occurs within a continuum whereby processes of both fracture and abrasion combine, generating intermediate grain forms. The style of deformation experienced is controlled by the nature of the bedrock and the overall strain imposed on the till. At ...