Observing Ice Sheet/Ocean Interactions in a Greenland Glacial Fjord
Arctic Research Initiative
2009 Funded Project
Mass loss from the Greenland Ice Sheet rapidly increased over the last decade raising concerns for sea-level rise and for the impact of the excess fresh water on the ocean circulation. The mass loss is primarily due to the acceleration and thinning of outlet glaciers and has been attributed to changes in conditions at their termini, in deep fjords where the ice extends several hundreds of meters below sea-level. The fact that the ocean around Greenland exhibited a 1-2 ºC increase at roughly the same time has prompted numerous scientists to conclude that the ice sheet’s changes have been triggered by ocean warming. This new hypothesis, with potentially profound implications for our climate system, is, however, largely unverified because of the chronic lack of measurements from the ice/ocean boundary. Obtaining such measurements is thus crucial to both understanding and modeling the ice sheet and its variability.
Making measurements at the edge of Greenland’s outlet glaciers is nontrivial. The deep, long fjords are remote, typically uncharted and choked with sea-ice and deep-reaching icebergs. Traditional ocean-observing methods, designed for more benign environments, are likely to fail in such extreme conditions. Here, we propose to fill a fundamental gap in observing and understanding ice sheet/ocean interactions through a multi-faceted, targeted experiment in one large Greenland glacial fjord. The field measurements will utilize a combination of newly developed or adapted technologies which include:
i) profiling sensors deployed from a ship and a helicopter to map the summer ocean properties in the fjord and near the glacier’s edge
ii) bottom moored instruments (to avoid collision with icebergs) to provide long-term information on the ocean properties and circulation in the fjord
iii) specially designed, acoustically tracked floats to reach the ice-choked region at the edge of outlet glacier.
This work takes advantage of a ship of opportunity (an icebreaker with a helicopter) and builds on a pilot program recently conducted by one of the PIs (Straneo). The goals are 1) to obtain new, unprecedented measurements from a crucial region in the Earth’s climate system; and 2) to develop and test techniques that will allow such measurements to be made in larger full-blown experiments. It brings together the diverse expertise of three WHOI scientists and seeks to establish WHOI’s leadership in the rapidly growing field of ice-sheet/ocean interactions.