Glaciology seminars

Frank Paul presents early findings from the Karakoram Anomaly Cross-ECV project. The research combines satellite Earth observations with climate data to improve glacier mass-balance modelling in a region where measurements are sparse and glaciers are changing rapidly. The talk examines how these complementary records can help monitor Karakoram glacier dynamics.

Satellite sea-ice concentration retrievals are commonly assimilated using a constant observational uncertainty of 0.10–0.15. This research instead estimates uncertainty within the assimilation system through an iterated Desroziers diagnostic constrained to the physical 0–1 concentration range. Two passive-microwave products and one optical product in both hemispheres show strongly state-dependent errors: roughly 0.02–0.10 near open water or complete cover, and 0.20–0.35 around half cover. Complete cover during melt remains difficult to constrain because the model rarely reproduces it. Comparisons among three collocated satellite products and published retrieval uncertainties support the pattern. The results suggest constant uncertainty overweights intermediate retrievals and underweights values near zero and one, with thin and ponded ice contributing errors beyond instrument noise.

We investigated meteorological controls on seasonal deep-seated motion of the Barry Arm landslide, a ~500 Mm³ slope instability with tsunamigenic potential in Prince William Sound, Alaska. Using ground-based synthetic aperture radar, we identified periods of deep-seated displacement, and combined airborne ice-penetrating radar with a glacier melt model driven by local meteorological data to evaluate the role of Cascade Glacier, which covers much of the area contributing groundwater to the landslide. We show that an over-deepened section of Cascade Glacier adjacent to the most active part of the landslide likely acts as a transient reservoir that routes meltwater to the landslide and that deep-seated landslide motion initiated only when modeled glacier discharge exceeded a distinct threshold.

The coupled hydrology and ice dynamics of the higher elevations of the Greenland Ice Sheet, where ice is beyond a kilometre thick, remains poorly understood. This lack of knowledge is a significant source of uncertainty in the models used to project the ice sheet’s sea level rise contribution, both in terms of surface mass balance and the potential for dynamic drawdown. I will discuss some of our recent and ongoing work towards (1) improving the accuracy of partitioning between refreezing and runoff processes, and (2) capturing the impact of surface meltwater on ice sliding where the ice sheet is more than a kilometre thick.

Arctic landscapes are among the most vulnerable on Earth to climate change, largely due to the rapid degradation of permafrost. In steeper bedrock-dominated terrains, warming permafrost can lead to increased sediment production via mass wasting events and amplify the delivery of sediment to channels and lakes. However, there is a fundamental lack of data on current rates of sediment production and transport in Arctic watersheds, especially those still responding to post-glacial perturbations, making it impossible to predict the responses and rates of sediment transport processes under future climate change. In this talk, I will present findings from a field-based study of the Black Mountain catchment in the Aklavik Range (Canada). This site was chosen due to the presence of an alluvial fan that post-dates the retreat of the Laurentide Ice Sheet (LIS), providing a closed system where we can consider how both paraglacial and periglacial mass flow processes have influenced physical weathering and transport rates through time.