Measuring Greenland’s Helheim Fjord Circulation Using the Custom ADOS Drifter
Greenland’s Helheim Glacier appears to be rapidly retreating. The present hypothesis is that warming ocean temperatures are accelerating the glacier’s melting rate at its terminus. The processes that link fjord circulation and glacier melting rates, and how they modulate the position of Helheim Glacier’s terminus, are largely unknown and difficult to study because of glacier calving and the locally ice-strewn waters.
The Lagrangian Drifter Laboratory designed and fabricated a low-cost, yet accurate Autonomous Drifting Ocean Station (ADOS) to measure the fjord circulation while moving with the flow. The ADOS is a modified 35 cm spheroid surface float that while measuring sea surface temperature, wind speed and direction, and barometric pressure hosts a 200 m depth instrumented cable that measures temperature and pressure. The latest custom version is air-deployable.
The first prototype chain was deployed by helicopter on August 7, 2019, in a region with substantial ice coverage. The initial mission lasted for 18 days until local fishermen removed the instrument and abandoned it on land. The goal of the program is to use the ADOS to make observations spanning at least one seasonal cycle.
Accurate, autonomous oceanographic sensors that observe oceanographic and atmospheric parameters at the ocean-atmosphere interface will provide fundamental data needed to elucidate the physical processes that control the state of the glaciers as they respond to varying ocean and atmospheric conditions.
This work is being funded by the Heising-Simons Foundation.