Basal melting of marine‐terminating glaciers, through its impact on the forces that control the flow of the glaciers, is one of the major factors determining sea level rise in a world of global warming. Detailed quantitative understanding of dynamic and thermodynamic processes in melt‐water plumes underneath the ice‐ocean interface is essential for calculating the subglacial melt rate. The aim of this study is therefore to develop a numerical model of high spatial and process resolution to consistently reproduce the transports of heat and salt from the ambient water across the plume into the glacial ice. Based on boundary layer relations for momentum and tracers, stationary analytical solutions for the vertical structure of subglacial non‐rotational plumes are derived, including entrainment at the plume base. These solutions are used to develop and test convergent numerical formulations for the momentum and tracer fluxes across the ice‐ocean interface. After implementation of these formulations into a water‐column model coupled to a second‐moment turbulence closure model, simulations of a transient rotational subglacial plume are performed. The simulated entrainment rate of ambient water entering the plume at its base is compared to existing entrainment parameterizations based on bulk properties of the plume. A sensitivity study with variations of interfacial slope, interfacial roughness and ambient water temperature reveals substantial performance differences between these bulk formulations. An existing entrainment parameterization based on the Froude number and the Ekman number proves to have the highest predictive skill. Recalibration to subglacial plumes using a variable drag coefficient further improves its performance.

The accelerated melting of Greenland's glaciers contributed to a net global mean sea level rise of 7.5 mm during the years 1992-2011(Church et al., 2011. Around Greenland, the basal and surface melt water enters the ocean largely through glacial fjords, mainly as subglacial discharge at the grounding lines of marine-terminating glaciers or as subglacial melt fluxes at the ice-ocean interface (Straneo & Cenedese, 2015). Increased melting at the ice-ocean interface it thought to be responsible for the acceleration of many of Greenland's marine terminating glaciers and thus to have contributed to the sea level rise. Some large Greenland fjords are covered with ice tongues of marine-terminating glaciers such as the Nioghalvfjerdsfjorden, also called 79°N glacier fjord (Mayer et al., 2018), and the Petermann Gletscher (Münchow et al., 2014). For these glaciers the link between submarine

Climate is changing due to global warming and many of the observed changes since the 1950s are unprecedented over many centuries to many thousands of years (IPCC, 2021). Since the end of the 20th century, the frequency and intensity of the strongest storms have been increasing in the North Atlantic (IPCC, 2013). Damage resulting from storm surges, sea level rise, and coastal flooding presents a major risk for Europe (IPCC, 2014). It is thus essential to investigate how extreme sea levels and storm surges change in a warming climate, in the perspective of predicting them and adapting coastal areas accordingly to future changes.Extreme high sea levels are the joint effect of mean sea level (MSL), tide, and storm surges. Storm surges are generated during extreme weather events such as extra-tropical storms or cyclones, and result from strong, large-scale atmospheric forcing (e.g., Dangendorf et al., 2016). The European coasts are regularly impacted by mid-latitude extra-tropical storms, which cause large surges, i.e., greater than 1 m. This may lead to huge economic losses and sometimes loss of human life. For example, the storm Xynthia hit the French coast severely on February 27 and 28, 2010, causing a large surge of 1.53 m in the harbor of La Rochelle (see location on Figure 1). This was the highest surge ever observed since the installation of the tide gauge in 1997; its return period was estimated to be greater than 100 yr (Pineau-Guillou et al., 2012). This exceptional storm event caused a major coastal flooding (Bertin et al., 2014). Forty-seven people were killed, around 10,000 people had to be evacuated, and the losses were estimated to more than 2.5 billion Euros (Genovese & Przyluski, 2013).