Start Date/Time: Thursday, April 18, 2013, 11:30 AM
Ending Date/Time: Thursday, April 18, 2013, 12:30 PM
Location: ATG 154 (near Seismo Lab in the basement)
ESS Research Assistant Professor Candidate Talk - Glaciology Technical Talk
Speaker: Michele Koutnik
Topic: Effect of ice-divide migration on ice-core records
Transients in accumulation and in ice flow can drive ice-divide migration. However, it is likely that dynamical changes initiated near the ice-sheet margin control ice-divide position. Interior ice responds to modern marginal changes, and larger marginal changes (for example during glacial-interglacial transitions) likely led to larger interior response. I will discuss how flux perturbations that drive ice-divide migrations on hundreds to thousands of year timescales can affect the thinning function, which alters the depth-age scale, the ice-temperature profile, and the modeled ice-core accumulation history at ice-core sites on the divide or on the flank of the divide.
Since we do not yet know the actual migration history of ice divides, I will explore the response of interior ice to plausible changes in ice flow on various timescales to assess if migration needs to be considered when modeling ice-sheet history to aid ice-core interpretation. I will show model results for an ice sheet with the geometry of Central Greenland between the GISP2 and GRIP core sites. This is an important site to study because it is distinct having two nearby deep ice cores, observations suggest that the divide migrated in the past few thousand years, and I present how a past episode of migration can explain an observed offset between these two ice-core records.