GROCE - Greenland Ice Sheet Ocean Interaction

Investigation of the Interactions Between the Greenland Ice Sheet and the Surrounding Ocean

The joint research project GROCE (Greenland Ice Sheet Ocean Interaction) is a research initiative funded by the German Federal Ministry of Education and Research, involving eight German institutes and universities. The goal of this project is to improve the understanding of the dynamics of the changing Greenland Ice Sheet. To achieve this, the interactions connecting the North Atlantic, the Arctic Ocean, and Greenland's glaciers need to be studied in greater detail. More information can be found on the project's website.

Our oceanographic work focuses on measurements near the calving front of the 79° North Glacier, Greenland’s longest remaining floating glacier tongue (80 x 25 km, ice thickness: 100 to 600 m). In 2016, we reached the glacier’s calving front with R/V Polarstern—the first research vessel ever to do so—and discovered an astonishingly rapid inflow of warm Atlantic water beneath the glacier tongue.

To record the heat transport into the ocean-filled glacier cavity throughout an entire year and observe potential seasonal variations, we deployed measuring instruments along the calving front between 2016 and 2017. These instruments continuously measure temperature, salinity, and current velocities at various water depths.

Our oceanographic time series reveal inflow velocities of up to 50 cm per year and a heat transport leading to average melt rates of 13 m per year at the underside of the glacier tongue. Interestingly, the highly complex seafloor topography in front of the calving front plays a crucial role in controlling the oceanic heat transport beneath the glacier tongue—and thus the melt rates at its base. Consequently, the stability of the glacier tongue likely depends on large-scale changes in the properties of Atlantic water (temperature and salinity), which are influenced by processes occurring hundreds of kilometers offshore.