Aminat Ayomide Ambelorun
(Advisor: Dr. Alexander Robel)
will defend a doctoral thesis entitled,
Modeling Iceberg Calving: Stochasticity and Local Sea-Level Coupling
On
Monday, August 24 at 1:00 p.m.
Ford ES&T, Room 3243 (The Ocean Room)
Abstract
Iceberg calving, the fracture and detachment of glacier ice into the ocean, is one of the dominant sources of ice loss from the Antarctic and Greenland Ice sheets. Despite its importance, calving remains one of the largest sources of uncertainty in projections of future sea-level rise from ice sheet mass loss. This uncertainty arises largely because calving is governed by fracture processes that large-scale ice sheet models cannot resolve directly, along with other interacting physical processes that are not fully represented. These processes produce calving events across a wide range of spatial and temporal scales. However, most large-scale ice sheet models generally parameterize calving using deterministic laws that neglect this intrinsic variability. In this thesis, I address two unsolved problems in the modeling of iceberg calving. First, I develop a mathematical framework for representing iceberg calving as a stochastic process in ice sheet models. Stochastic simulations of the Amundsen Sea Embayment in West Antarctica in a large-scale ice sheet model show that stochastic calving accelerates ice loss by 8.4–32.6% after 100 years relative to simulations with deterministic calving. Second, I identify a positive feedback neglected in previous coupled ice sheet-sea level-solid Earth studies. Simulations of the Amundsen Sea Embayment show that coupling local sea level to both calving and ice flow increases ice volume above flotation loss by 86% after 200 years relative to an uncoupled control. I conclude by discussing how these results motivate stochastic calving parameterizations, improved observational constraints on calving variability, and the inclusion of stochastic calving and coupled calving–sea-level feedback in future ice-sheet projections.
Committee:
•
Dr. Alexander Robel – School of Earth and Atmospheric Sciences (advisor)
•
Dr. Winnie Chu – School of Earth and Atmospheric Sciences
•
Dr. Lilian Dove – School of Earth and Atmospheric Sciences
•
Dr. Annalisa Bracco – School of Earth and Atmospheric Sciences & Senior Scientist, CMCC Foundation
•
Dr. Hélène Seroussi – Thayer School of Engineering, Dartmouth College