Teilprojekt 11: Wechselwirkungen des Schmelzwassers im Ozean

Recent studies using climate models and paleocenographic records point to far-reaching impacts offresh water flux from the melting Greenland Ice Sheet (GrIS) on the subpolar Atlantic Ocean circulation, convection and overturning, the European climate and the sea level fingerprint in different regions of the World Ocean. Relatively little is known however about its impacts on oceancirculation around Greenland. In particular, interaction (mixing) of the glacier melt water withwarmer water masses on the Greenland shelf may lead to a nonlocal negative feedback on theocean heat flux toward marine-terminating glaciers and thus on their basal melt rates. The glaciermelt water pathways on the shelf, mixing and feedbacks are not well understood as neithermodeling studies focused on large-scale impacts of the GrIS melt nor the sparse observationsresolve the circulation around the Greenland adequately. The joint effort of the GROCE Verbund offers an integrated and detailed insight into the ocean glacier interactions relevant to the GrIS melt with the Northeast Greenland Ice Stream (NEGIS) and in particular, the 79-North Glacier (79°NG) being the focus and a study case. This Subproject (TP11) considers ocean circulation around Greenland and its changes due to increased glacier melt, interaction of melt water with the ambient ocean, and the feedbacks on the melting processes. We will employ Lagrangian framework which is tailored to study water mass pathways. We will perform simulations of large numbers of Lagrangian particles representing water masses and allowing astatistical description of model water properties (temperature, salinity) along particle trajectoriesand of the mixing processes. Lagrangian trajectories have an interpretative quality by connecting changes in velocity or water properties at different locations. Our project will thus provide linking and contextualization of the results from the other Verbund partners. Our Lagrangian framework will be embedded in model simulations of TP9 (General Estuarine Transport Model, targeting ocean circulation close to the 79NG) and in the FESOM (Finite Element Sea Ice-Ocean Model) high resolution simulations performed by TP10. We will also collaborate tightly with other TPs regarding the setup of our model experiments, comparison with observations and interpretation of the results. The long-term vision is to develop, together with our Verbundpartners, a modeling-analysis framework that could be applied in other regions of Greenland and Antarctica and lead to future improvement of prediction of the glacier melt and its impacts.