CIRES Special Seminar: Brent Minchew
Oceans and ice: How ocean tides influence inland ice flow
by Brent Minchew - NSF Postdoctoral Fellow, British Antarctic Survey
Abstract: The vertical motion of ocean tides modulates horizontal ice flow up to nearly 100 kilometers inland in some Antarctic ice streams. The amplitudes of modulation can exceed 20% of the secular flow speed and have been shown to occur at the beat frequency of the two semi-diurnal tidal constituents. This phenomenon provides a useful case where the response of an ice stream to a well-constrained forcing function is observable. Traditionally such observations have been made with individual GPS sites, but here I describe the methodology and results for a full 3D, time-dependent inversion from remotely sensed data. This first-of-its-kind observational dataset provides ice-stream-scale measurements of 3D secular and time-varying surface velocity on Rutford Ice Stream, West Antarctica. We inferred these velocity fields from 9 months of continuous synthetic aperture radar observations collected from multiple satellite viewing geometries with the 4-satellite COSMO-SkyMed constellation. The resulting velocity fields elucidate the spatiotemporal characteristics of the response of ice flow to ocean tidal forcing, providing insights into the mechanisms driving tidal-timescale flow variability, ice rheology, and the mechanics of the ice stream bed.
Bio: Brent Minchew is a glaciologist specializing in applications of remote sensing and glacier mechanics. He recently received his PhD in geophysics from Caltech where he mainly studied the mechanics of deformable glacier beds. Brent is en route to complete his postdoctoral fellowship at the British Antarctica Survey in Cambridge, UK, where he will study spatiotemporal variability in ice stream flow in West Antarctica by constraining numerical ice flow models with remote sensing and other geophysical observations. His other research interests include applications of existing remote sensing instruments to hazard mitigation and the spatial distribution and environmental controls on landslides. Before pursuing a PhD at Caltech, Brent completed B.S. and M.S. degrees in aerospace engineering from the University of Texas at Austin.