Estuaries comprise of the region within coastal water bodies where terrestrial fresh water interacts with oceanic salt water. Classically, the turbulent mixing between these water masses results in an inflow of saline water and an outflow of fresh water – the estuarine circulation or exchange flow. This basic circulation is a wide-spread phenomenon of the coastal ocean, occurring in river mouths, underneath floating glaciers and even in the Baltic Sea as a whole. Under certain conditions, such as in regions with intense evaporation, with a strong wind-driven circulation or ice cover, the classical circulation pattern may be altered or even inverted.

Read more … Estuarine dynamics

We study how fronts, filaments, and eddies shape air–sea exchange by controlling stratification, mixing, and vertical transport in the ocean’s surface boundary layer (SBL). This upper layer, typically characterized by relatively weak density stratification, connects the atmosphere to the ocean interior by mediating fluxes of momentum, heat, freshwater, and gases, while strongly influencing the light–nutrient environment that regulates primary productivity.

Read more … Surface boundary layer dynamics

Sea level variability could not only affect the air-sea exchanges via surface ocean dynamics but also risk the coastal communities/cities from hazards such as inundation, erosion and retreat. Changes of sea level are governed by various processes on small to large scales, both in space and time, e.g., wind waves, tides, meteo tsunamis, storm surges, mean sea level rise etc. We study these sea level changes as well as their interaction with hydrodynamics, turbulence and sediment transport in estuaries and coastal seas.

Read more … Sea level dynamics

Sediment transport is one of the most critical issues in eco-environmental systems either in fluvial and estuarine environment or in coastal systems. It is not uncommon that the different sediment particles, from mud to gravel, are existing in one coastal system, in which these wide range of sediments could also interact with each other. Our study focused on the sediment dynamics across the estuaries and coasts based on process-based numerical modelling where their interactions between coastal and estuarine dynamics are included, associated with the impacts from wave shoaling and propagation and sea level dynamics.

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Polar regions are strongly affected by global warming and heat up rapidly under anthropogenic climate change.  In consequence, the ice in Greenland and Antarctica melts with increasing rates, which is a major contributor to global sea level rise.  We study the melting of glacial ice tongues that flow into the ocean and are thus not only melted by the sun from above, but also from below due to processes at the ice–ocean interface.

Read more … Ice-Ocean interactions

Coastal oceans are complex ecosystems. Their description requires an interdisciplinary approach. In addition to detailed measurements, realistic model simulations are necessary to understand the sophisticated interplay of all relevant processes. For this we develop advanced model techniques and diagnostics.

Read more … Model development and diagnostics