The PhD defence and trial lecture will be held in Auditorium 1 in The Geology Building. In some cases, it will be possible to attend the trial lecture and dissertation digitally, in that case a link to Zoom will be posted.
Trial lecture
Wednesday 11 September, 10:15-11:00, Aud 1, The Geology Building:
Climate change impacts on the dynamics of Norwegian coastal waters and fjords
Conferral summary (in Norwegian)
Norske kystområder kjennetegnes av lange fjorder, flerfoldige øygrupper og trange sund. Vinden skaper bølger som forplanter seg mot kysten, og tidevannet kan være en viktig pådriver for sirkulasjon innaskjærs. Denne avhandlingen viser hvordan sterke tidevannsstrømmer samt bølger på overflaten kan påvirke sirkulasjonen og transport av partikler, som for eksempel lakselus og plast, i kystnære strøk og nær havoverflaten. Avhandlingen presenterer nye forklaringsmodeller for hvordan virvler oppstår i trange sund og påvirker sirkulasjonen nær trange sund, og undersøker hvordan bølgedreven transport mot kysten kan beregnes.
Main research findings
Popular scientific article about Espenes’s dissertation:
Near-shore dynamics and transport processes due to tide-topography interactions and wind waves
Numerical ocean models simulate the Eulerian ocean circulation and are used to assess transport of particles near the coastline, such as salmon lice, plastics and other pollutants. Such simulations account for dynamic processes acting over a wide range of length and time scales. The processes can be highly non-linear and interact with the coastline. Comparisons of model results to observations can develop our understanding of the processes the ocean models should represent, and how to design models that account for the processes. This doctoral thesis focuses on tide-topography interactions, and transport of particles towards within the near-shore environment.
In the doctoral study, a new dynamical description of how eddies form, detach and propagate away from narrow tidal channels is developed. Thereafter it is demonstrated that the vorticity generated at such channels can force time-mean circulation around fjords. This shows that the local small-scale tidal dynamics in narrow channels can upscale and influence the ocean circulation over a much greater area. We lastly investigated how surface gravity waves act to transport particles towards the coastline, where the aforementioned tidal dynamics is relevant, by looking at how the wave driven transport can be parameterized.
In short, this doctoral work gives new insight into processes relevant to particle transport in the near-shore environment and how to model them. These insights can be helpful when designing future systems to model ocean transport along the Norwegian coast.
Photo and other information:
Press photo: Håvard Espnes, portrait; 900px. Photo: Private
Other photo material: Photo with description and credit as specified in the article above, size 1280px.
