30.11.2015: FB1-Seminar

11:00 h, Hörsaal, Düsternbrooker Weg 20

Abstract:

Mass loss from the Greenland ice sheet quadrupled over the past two decades, accounting for a quarter of the observed global sea-level rise, and contributing to the freshening of the subpolar North Atlantic with postulated consequences for the convection and dense water production. One possible cause of this acceleration is enhanced submarine melting at the glaciers' terminus driven by the inflow of warm Atlantic waters from the Greenland shelf into the glacier fjords. The pathways, time variability and driving mechanisms of the Atlantic inflow toward the glaciers are poorly constrained by existing observations, hindering our understanding of the impact of the warming climate.

In this talk, I will present results from a high-resolution model study focused on Atlantic waters intruding into the Sermilik-Helmheim fjord-glacier system, SE Greenland. The regional ocean model configuration (MITgcm, Johns Hopkins University) features a 2km- and 15m grid spacing in horizontal- and vertical directions, respectively, a wind forcing by Era-Interim resolving local atmospheric circulation patterns and an improved representation of the bathymetry incorporating recent ship- and seal-borne measurements. The regional ocean model is complemented by Lagrangian particle simulations. We quantify time variability of the warm Atlantic inflow into the the Sermilik fjord on intraseasonal-to-daily scales, and the importance of the atmospheric forcing in driving the inflow. The inflow sources, pathways and attendant water mass transformation processes are quantified with backward-traced O(10,000) Lagrangian particles.

Our study highlights the importance of proper model representation of topographic features steering the modeled inflow, and of adequate temporal and spatial resolution of the warm intrusions into the fjord. Based on the model results, we give suggestions to the future observational systems on key monitoring sites relevant to the warm Atlantic inflow toward the Sermilik-Helmheim fjord-glacier system.

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