Ice flow dynamics during retreat induced separation of a tributary glacier

Most glaciers around the world are currently in retreat, with ongoing global warming the primary cause. Much attention has been paid to the rate and magnitude of ice retreat, but fewer studies have considered changes in ice flow dynamics during ice retreat. In this study we propose focusing in on a rapidly retreating outlet glacier draining the Southern Patagonian Icefield: Glaciar Upsala. Glaciar Upsala's ice front has retreated more than 10 km over the last 50 years, and the entire glacial drainage basin has thinned by more than two meters in the 21 century. The rapid front retreat has resulted in one large tributary glacier, Glaciar Bertacchi, being partially detached from the main glacial trunk. Using a combination of Landsat and Sentinel satellite imagery dating back 30 years, we aim to consider changes in ice flow velocity and direction around the confluence of the glaciers during their transition from one single outlet to two distinct glaciers.

This analysis is being conducted with the use of a Matlab based particle tracking algorithm that has been modified to efficiently run long time series, while automatically detecting, deleting and interpolating outlier values. The rapid flow velocities of Glaciar Upsala, up to several metres a day, make the particle tracking velocity technique particularly appropriate. A sharp velocity and flow-direction change exists between the Upsala glacier the tributary Bertacchi glacier, with further work aiming to determine how this pattern has evolved through time.