Event

The Department of Earth & Environmental Science

University of Pennsylvania

Invites you to attend a EES Seminar Series

Friday, November 3rd - 3:00 PM

"Modeling Ice Deformation in Ice Sheets"

Most of the mass loss from the Antarctic Ice Sheet occurs due to rapid ice flow through glaciers and ice streams. Ice flow is generally modeled through a constitutive relation, which relates the rate of deformation to applied stress. While it is common the use a single power-law form of the constitutive relation known as Glen’s Law, the constitutive relation can be more generally represented as a sum of power laws where each term represents a different mechanism of ice deformation and is dependent upon the underlying parameters of each mechanism, such as its activation energy and stress exponent. These parameters have significant implications for how we model the relative contributions of different deformation mechanisms, which in turn affects the effective rheology of ice and outputs of ice-flow models. Here, we apply a composite flow law, a steady-state grain size model, and a thermomechanical model to elucidate the dominant deformation mechanism in different regions of the Antarctic Ice Sheet and its sensitivity of the kinetics of ice flow. We propose a framework for estimating the value of the stress exponent n from this suite of models. Our results help to explain the range of value of the stress exponent n previously inferred in laboratory and field studies and our method provides a straightforward way of parameterizing the effect of varying flow conditions on the parameters in the constitutive relation for ice flow.

Dr. Meghana Ranganathan

NOAA Climate & Global Change Postdoctoral Fellow

Georgia Institute of Technology

Meghana Ranganathan is a NOAA Climate & Global Change Postdoctoral Fellow at the Georgia Institute of Technology, working with Dr. Alexander Robel on understanding the coupling between ice fracture and ice flow in ice sheets. Previously, she received her Ph.D from MIT under the advising of Dr. Brent Minchew, and beginning in July 2024, she will be starting as an Assistant Professor at the University of Chicago in the Department of Geophysical Sciences.