Recent patterns of velocity and elevation change, and their associated drivers, Hubbard Glacier, Alaska

Kurzfassung

Hubbard Glacier is a large, Alaskan tidewater terminating outlet measuring 123 km in length, making both the biggest calving glacier inside North America and the biggest non-polar tidewater glacier globally. Previous research has found that Hubbard Glacier experiences a unique seasonal cycle in glacier flow, with distinct slowdowns observed in the late summer and variations in flow speeds of up to 6 m d-1 through the year. To this date however, the quantification of this seasonality has been sparsely studied largely due to a lack of available datasets to enable its characterization. But, with the recent launch of a number of openly available remote sensing datasets, this study investigates the seasonality of Hubbard Glacier in unprecedented detail. Specifically, using surface velocities derived from SAR (Sentinel-1, TerraSAR-X, ERS-1/ERS-2) and optical imagery (Landsat, Sentinel-2), Hubbard Glacier’s flow speeds are detailed at the highest temporal resolution possible to allow for an in-depth exploration of its seasonality. This work aims to densify Hubbard Glacier’s seasonality record and extend velocity observations to present day. The velocity trends are compared to temperature reanalysis data to determine links between climate and flow speeds, which are used to hypothesize how Hubbard Glacier’s velocity may evolve in the future with a warming climate. Elevation change of Hubbard Glacier is also quantified over the 2000-2020 period (in five-year epochs). This allows us to determine if thickening or thinning of the glacier has occurred and how glacier dynamics may be responsible for the observed geometry changes. This research is a major update of our knowledge of how Hubbard Glacier is behaving dynamically and of critical importance for understand how climate change may impact large tidewater glaciers in Alaska and elsewhere.