The TRR 181 seminar is held by Prof. Inga Koszalka (GEOMAR) on
Unraveling the warm Atlantic Water inflow toward South–East Greenland glaciers from Lagrangian particle trajectories
at Leibniz Institute for Baltic Research Warnemünde, on January 17 at 1 pm.
Mass loss from the Greenland Ice Sheet quadrupled over the past two decades. The resulting fresh water flux into the ocean accounts for a quarter of the observed global sea-level rise and contributes to freshening of the subpolar North Atlantic, with major consequences for the meridional overturning circulation. The loss of Greenland ice has been attributed to increased melt of marine-terminating glaciers in the South-East and West Greenland. One possible driver of this melt is the warm Atlantic Water (AW) from the Irminger Basin penetrating onto the Greenland shelf and into the glacial fjords. The pathways of the AW inflow, its variability, and the driving mechanisms are poorly constrained by extant observations, however. This hinders our understanding of the attendant melting processes and thus our capability to assess and predict the impact of the melting Greenland Ice Sheet.
We use a high resolution ocean circulation model and a suite of Lagrangian particle simulations to study the warm AW flow toward the Helmheim-Sermilik, a major glacier-fjord system in South-East Greenland that has undergone rapid melting and retreat in the last two decades. The particle trajectories depict two distinct AW pathways from the Irminger Basin onto the shelf, and several recirculations emphasizing the role of the bathymetric features on the shelf in steering the flow. We map regions where the AW undergoes most intense water mass property change through mixing with the Polar Waters and transforms into a strongly modified water mass that reaches the fjords. Based on these results, we discuss strategies for future observing systems to monitor the intensity and properties of warm Atlantic inflow toward these glaciers. We include methodological remarks and future outlook for Lagrangian studies of the Greenland melt pathways.