Hot water drilling at Langhovde Glacier, East Antarctica

Ice discharge from fast flowing ice streams and glaciers play a key role in the mass budget of Antarctic ice sheet. Recent observations from satellites show speed up and thinning of such glaciers in West Antarctica. Glaciers in the Antarctic Peninsula accelerated after the disintegration of ice shelves, suggesting the reduction in the back pressure from the shelf ice as the cause of the acceleration. Warming ocean is suspected as the trigger of the ice shelf disintegration. However, field measurements at the interface of the ice sheet and the ocean is lacking so far. Most of the key processes are acting beneath the ice, which makes the problem difficult to understand by surface observations.

In 2011/12 austral summer season, we drilled through the floating tongue of Langhovde Glacier, a fast flowing outlet glacier in East Antarctica. Hot water drilling was performed at two locations near the grouding line and two boreholes at each sites were excavated to the bed. The boreholes told us that 400 and 430 m thick ice is underlain by 25 and 10 m deep sea water at the two sites, respectively. Temperature, salinity, and current sensors were inserted into the boreholes to measure physical properties of subshelf sea water. Borehole camera was inserted as well, and it captured interesting subshelf environment, including life beneath the shelf ice. Sensors were permanentoly installed in the boreholes for monitoring water pressure and ice temperature. On the glacier, GPS receivers are running continuously until the next season to measure ice speed variations driven by the ocean tide. These observations will be utilized to study the evolution of Langhovde Glacier under changing climate and ocean conditions.

In 2017/18, we visted Langhovde Glacier again to drill more boreholes on the floating ice. Drilling was performed at four locations, covering an area from the grounding zone to the glacier front. Measurements under the ice revealed seawater temperature and salinity distributions over the entire range of the subshelf cavity. Data indicates relatively warm ocean water enters into the deeper region of the cavity, supplies heat for basal melting, and upwells with meltwater along the base of the ice. We also carried out seismic and GPS measurements on the glacier to investigate short-term variations in the glacier dynamics. The data confirmed a strong influence of ocean tide on the glacier flow speed. Our study indicates a strong link between the glacier and the ocean, which provides a new insight into recent change observed in the Antarctic ice sheet.

We returned to Langhovde in 2021/2022 for our third drilling campaign. The goal of this season was to drill boreholes through grounded ice, which was achieved by 550-m deep drilling completed at about 1 km from the grounding line. By using three boreholes drilled at this location, pressure sensors, accelerometer, seismometer and thermistor chain were installed to study a link between subglacial conditions and glacier dynamics. Data from these boreholes gave us evidence of subglacial hydrology and its influence on glacier flow speed. Additional drilling was performed at two more locations downglacier to investigate the subglacial environment in the grounding zone as well as the exact location of the grounding line. We will learn more details of the glacier dynamics from measurements still in progress in the boreholes and on the glacier

Langhovde Glacier
Hot water drilling
Project members
Meeting
Field campaign 2011/12
Field campaign 2017/18
Field campaign 2021/22
Drilling and borehole video movies