9:00 AM - 9:15 AM
[ACC25-01] Short-term changes in the dynamics of lake-terminating glaciers, after the outburst of Lago Greve in Patagonia
★Invited Papers
Keywords:Calving glacier, Glacial lake, GLOF (Glacial lake outburst flood), Glacier dynamics
Rapid mass loss of mountain glaciers contributes to global sea level rise. Among the glaciers, calving glaciers show especially rapid shrinking as observed in Patagonia and Alaska. Because the number and volume of glacial lakes are increasing, better understanding of the lake-glacier interaction is demanded. However, the dynamics of the lake-terminating calving glacier is poorly understood. Proglacial lakes play an important role in the evolution of lake-terminating calving glaciers, by affecting ice flow speed and frontal ablation. GLOFs (glacial lake outburst floods) offer a unique opportunity to study short-term changes in the dynamics of glaciers flowing into the lake. In April–July 2020, an outburst event occurred at Lago Greve in the Southern Patagonia Icefield, the 4th largest glacial lake in the world. Here, we report the dynamic change of the lake-terminating glaciers in response to the drainage event of Lago Greve by investigating ice-front position, velocity, and surface elevation from 2016–2021.
The focus of this study is the northern front of Glaciar Pío XI and two ice-fronts of Glaciar Greve, which are flowing into Lago Greve. The positions of the ice fronts were measured with optical satellite imagery (Sentinel-2, Landsat 8 and PlanetScope). Glacier velocity was measured by applying a feature tracking method to the Sentinel-2 and Landsat 8 imagery. We also utilized velocity products of the RETREAT project. Glacier surface elevation change was measured by comparing 5-m resolution digital elevation models generated in this study from stereo-pair images of WorldView-1 and SPOT-6/7 satellites.
The velocity of the northern terminus of Glaciar Pío XI decreased after the event by 60% as compared to the mean speed from 2016–2019. Because of the deceleration of the northern front, main flow of the glacier switched to the southern terminus. The western terminus of Glaciar Greve advanced by 113 m from April 2020 to December 2021 in contrast to a retreating trend since 1985. The glacier surface elevation in the terminus region decreased by 11.9 ± 0.9 m in February–July 2020. The sudden ice-front advance and surface lowering implied that the glacier terminus acceleration by 20% upon the drop in the lake level and the change in the speed enhanced a longitudinal stretching flow regime. These results indicated a significant influence of the lake water level on the glacier dynamics, which induced different responses of glaciers flowing into the same lake.
The focus of this study is the northern front of Glaciar Pío XI and two ice-fronts of Glaciar Greve, which are flowing into Lago Greve. The positions of the ice fronts were measured with optical satellite imagery (Sentinel-2, Landsat 8 and PlanetScope). Glacier velocity was measured by applying a feature tracking method to the Sentinel-2 and Landsat 8 imagery. We also utilized velocity products of the RETREAT project. Glacier surface elevation change was measured by comparing 5-m resolution digital elevation models generated in this study from stereo-pair images of WorldView-1 and SPOT-6/7 satellites.
The velocity of the northern terminus of Glaciar Pío XI decreased after the event by 60% as compared to the mean speed from 2016–2019. Because of the deceleration of the northern front, main flow of the glacier switched to the southern terminus. The western terminus of Glaciar Greve advanced by 113 m from April 2020 to December 2021 in contrast to a retreating trend since 1985. The glacier surface elevation in the terminus region decreased by 11.9 ± 0.9 m in February–July 2020. The sudden ice-front advance and surface lowering implied that the glacier terminus acceleration by 20% upon the drop in the lake level and the change in the speed enhanced a longitudinal stretching flow regime. These results indicated a significant influence of the lake water level on the glacier dynamics, which induced different responses of glaciers flowing into the same lake.