Complex Behavior of a Turbulent Plume at the Calving Front of a Greenlandic Glacier
The authors, Shin Sugiyama (green parka), Naoya Kanna (blue parka) and Evgeny A. Podolskiy (black parka), during the observations at the calving front in July 2017.
Credit: Lukas E. Preiswerk
For the first time, scientists have succeeded in continuous monitoring of a subglacial discharge plume, providing a deeper understanding of the glacier-fjord environment.
As marine-terminating glaciers melt, the fresh water from the glacier interacts with the seawater to form subglacial discharge plumes, or convective water flows. These turbulent plumes are known to accelerate the melting and breakup (calving) of glaciers, drive fjord-scale circulation and mixing, and create foraging hotspots for birds. Currently, the scientific understanding of the dynamics of subglacial plumes based on direct measurements is limited to isolated instances.
A team of scientists consisting of Hokkaido University’s Assistant Professor Evgeny A. Podolskiy and Professor Shin Sugiyama, and the University of Tokyo’s JSPS postdoctoral scholar Dr. Naoya Kanna have pioneered a method for direct and continuous monitoring of plume dynamics. Their findings were published by Springer-Nature in the journal Communications Earth & Environment.
Freshwater and marine water have very different densities, due to the salts dissolved in marine water. As a result of this density contrast, when the meltwater — originating from the glacier surface — flows down the cracks and emerges at the base of the glacier, it starts upwelling causing the formation of subglacial plumes. The rising plume entrains nutrient-rich, warmer water from the deep that further melts the glacier ice. In light of the effects of global warming and climate change, which have caused a massive loss in the volume of glaciers, understanding how plumes behave and evolve is crucial for predicting both glacier retreat and fjord response.
The scientists conducted the most comprehensive plume monitoring campaign to date at Bowdoin Glacier (Kangerluarsuup Sermia), Greenland. It involved a chain of subsurface sensors recording oceanographic data directly at the calving front at different depths. Additional observations were made by time-lapse cameras, a seismometer, unmanned aerial vehicles, and etc. This high-temporal-resolution dataset was then subjected to a thorough analysis to identify connections, patterns, and trends.