Can Seismic Observations of Bed Conditions on Ice Streams Help Constrain Parameters in Ice Flow Models?. Issue 11 (26th November 2017)

• Record Type: Journal Article
• Authors: Kyrke‐Smith, Teresa M.; Gudmundsson, G. Hilmar; Farrell, Patrick E.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 11(2017)
• Page Start: 2269
• Page End: 2282
• Publication Date: 2017-11-26
• Subjects: ice sheets -- inverse modeling -- Pine Island Glacier -- bed conditions -- subglacial processes -- seismic measurements; Geomorphology -- Periodicals; 551.3
• DOI: 10.1002/2017JF004373
• Languages: English
• ISSNs: 2169-9003

Abstract

Abstract: We investigate correlations between seismically derived estimates of basal acoustic impedance and basal slipperiness values obtained from a surface‐to‐bed inversion using a Stokes ice flow model. Using high‐resolution measurements along several seismic profiles on Pine Island Glacier (PIG), we find no significant correlation at kilometer scale between acoustic impedance and either retrieved basal slipperiness or basal drag. However, there is a stronger correlation when comparing average values along the individual profiles. We hypothesize that the correlation appears at the length scales over which basal variations are important to large‐scale ice sheet flow. Although the seismic technique is sensitive to the material properties of the bed, at present there is no clear way of incorporating high‐resolution seismic measurements of bed properties on ice streams into ice flow models. We conclude that more theoretical work needs to be done before constraints on mechanical conditions at the ice‐bed interface from acoustic impedance measurements can be of direct use to ice sheet models. Key Points: We make new comparisons of ice sheet basal conditions estimated by two methods (model inversion versus seismic measurements) There is correlation between mean values of basal slipperiness and acoustic impedance when averaged over large enough length scales Seismic measurements of bed properties cannot be incorporated into models unless a physical theory is developed