[ESAC Student Seminar] Max Filter

“Constraining the sliding law exponent with traveling wave propagation on Columbia Glacier, Alaska”

The dynamic contribution from glaciers and ice sheets to sea-level rise is sensitive to the mechanics of slip at the bed. These mechanical processes are often described in terms of a sliding law, which relates drag and rate of slip at the bed. A power-law relation between drag and slip rate is often used in ice-flow models, and the value of the exponent helps to constrain the mechanical processes that allow for slip. Direct observations of the material properties of glacier beds that affect this relationship, however, are often prohibitively challenging, especially at the spatial extents and resolutions required for accurate modeling of sea-level rise. In this work, we show that useful physical bounds on the sliding law exponent, and thus mechanisms of slip, can be inferred from a time series of remote sensing observations of surface velocity and elevation. Surface velocity measurements are used to quantify the characteristics (phase velocity and attenuation length) of traveling waves arising from annual and multi-annual forcings. Here, we compute these characteristics of traveling waves on Columbia Glacier, Alaska using a time series of TerraSAR-X-derived surface velocity data from 2011 to the present and find that the bed is effectively plastic, meaning that drag is largely insensitive to the slip rate. In general, this method can be applied to other glaciers and ice sheets with surface velocity data of sufficient temporal density to model a repeating annual signal, making it scalable to the spatial extents and resolutions required by sea-level rise models.

ESAC Student Seminar Series

A forum for students and postdocs to share recent research, hone presentation skills, and build community among peers, sponsored by the EAPS Student Advisory Committee. Open to current EAPS graduate and undergraduate students and postdocs. Typically hosted on Thursdays during the semester, including pizza lunch.

Contact: esac.officers@gmail.com