Tidally-induced turbulent mixing in a silled fjord

Essential regions of the marine ecosystems along the coast of Norway are situated inside fjords. Further, a large number of aquaculture facilities are found in fjords, and fjords make up a recreational area for millions of Norwegians. With a few exceptio ns, Norwegian fjords include a sill near the opening. The sill is essential for almost all fjord processes: it forms a barrier for the deep water in the fjord, which has a strong impact on the stratification there. The sill barrier also strongly influence s the water mass exchange between the fjord and the ocean in general, and the level of eutrophication in the fjord in particular. Thus, the sill is an obstacle for sediment transport, and its presence is vital for the oxygen conditions in the fjord's deep water. Understanding and being able to model the spatio-temporal variability of mixing in a fjord is essential in any study that involves marine ecology, for the reasons stated above. This is particularly the case when effects of projected changes in th e fjord's physical environment are investigated. In this project, we will examine the causes of and regional distribution of mixing in a fjord. A primary focus will be on the generation of internal waves at the sill and their contrubution to turbulent mi xing when they eventually break. This will be done by 1) applying novel techniques in numerical modeling and 2) conducting a dedicated observational campaign.