Project title: Identifying glacial melt processes in Greenland fjords
Principal investigator: Anna Wåhlin
About the project:
Reliable representation of mixing processes is needed for a correct estimation of ocean budgets and global flows of energy, freshwater, salt, nutrients and carbon, and better knowledge in this area will lead to more reliable models for prediction of climate and sea-level rise.
An inherent uncertainty is that the nonlinear processes that lead to the energy cascade from large to small scales are not possible to solve analytically even in simplified forms, and that they are prone to numerical instability.
Numerous laboratory experiments have been performed for example in pipes and channels to quantify the energy cascade. Much fewer experiments have been conducted in the ocean, where fundamental knowledge gaps still exist. In this project we will examine the interaction of the buoyancy-driven (forced by glacial meltwater) and the shelf-driven circulation in three Greenland fjords, and the dynamics in the near-ice zone.
Rapid mass loss from the Greenland Ice Sheet has sparked interest in its glacial fjords since the anomalous freshwater thus discharged from Greenland is transformed by fjord processes before being released into the large-scale ocean. Knowledge of the fjords’ dynamics is thus key to understanding global ocean circulation and climate. The deep sills and grounded glaciers of Greenland’s fjords make them unique systems that deviate from present understanding of fjord circulation.
The mixing processes in the fjords will be investigated using ship-based instrumentation (CTD, MSS) as well as similar instruments carried by our AUV Ran. In each fjord we will perform two AUV missions - one underneath and near the base of the ice melange in the inner fjord, and one near the seabed in the inner fjord. From the mission near the ice melange we will get information about the mixing properties of the ice-water mixture and any buoyant meltwater plumes. From the mission near the seabed we will get information about historical changes of the ice conditions in the fjord. During the course of the AUV missions we will occupy three transects across the fjord and one along-fjord transect with the ship, stopping at regularly-spaced CTD stations where we will also get MSS microstructure data.
