The Laboratory of Hydraulics, Hydrology and Glaciology received funding from the SPI to perform fieldwork in summer 2019 on Bowdoin Glacier, an outlet glacier of the Greenland icesheet. This glacier is quite special, because despite its high flow velocity (up to 2m/day where the glacier ends in the sea), it is possible to walk on the glacier. Normally, the fast flow of Greenland’s outlet glaciers makes them inaccessible: due to the high velocity, fractures form on the glacier surface which makes it impossible to walk on the glacier. However, on Bowdoin Glacier, there is a walkable moraine with little surface fractures, which allowed us to walk all the way to the glacier front. Therefore, we were able to install instruments measuring ice flow and seismic waves, right at the glacier front. This is unique for an area that is normally only observed through remote sensing.
Though well accessible, the glacier front is a dangerous area because icebergs can suddenly break off from the glacier’s ice mass. This breaking off of icebergs is called calving, and is responsible for approximately half of the ice mass loss of the Greenland ice sheet. Due to this risk, one must keep stays near the calving front to a minimum and always listen carefully to the sound of the glacier: it is easy to hear the opening up of fractures and sometimes it even seemed like we could feel the glacier vibrate underneath our feet shortly after the initiation of a fracture. During field work in previous years, there had been large calving events, and they were announced by a big fracture on the glacier’s surface that formed several days before the iceberg broke off. This alerted the expedition members in advance and they knew they should not go beyond this big fracture. However, this year we reached the glacier front one morning and noticed that over night a ~50x700m large piece of the glacier had calved off. This shows once more that ice-dynamic processes, and in particular iceberg calving are versatile and not fully understood yet.
Eef van Dongen is a PhD student at ETH Zurich. This field note relates to her field trip to Bowdoin Glacier (Greenland) in summer 2019 funded by a SPI Exploratory Grant.
Header photograph: Eef van Dongen