Geophysical fluid dynamics

Most of the activity within this field at Mechanics Division, Univerisity of Oslo, is related directly to the oil activity on the Norwegian continental shelf. The oil industry and the Norwegian Research Council has funded many of the research projects on ocean modelling and prediction of waves and currents. These projects have also provided opportunities for students to participate in project work and several cand scient and dr. scient students have written their thesis on problems related to these projects.

Tidal models

Numerical simulation models for the tides in the Nordic Seas and the Norwegian continental shelf and coastal waters have been developed through the activity under several projects. The results are published in reports and journal articles and have become widely used by engineers and oceanographers.

Lee waves and eddies

Studies of three-dimensional lee-wave pattern in the air flow behind isolated islands started around 1976 when high resolution satellite images became available. These images show that under certain atmospheric conditions regular vortex streets and lee-waves develop behind Jan Mayen in the Norwegian Sea. The lee-wave pattern resemble the classical ship-wave pattern. Similar wave pattern were found also behind Bear Island and Hopen in the Barents Sea.

Storm surge models and storm response

Work on the effect of wind and atmospheric pressure on the sea level started in 1972 after the exceptional large and destructive storm surge along the west coast of Norway from Statt to Lofoten 2-3 November 1971. The first numerical model for prediction of storm surges was developed at the institute around 1978. The model was latter adapted for operational forecasting at the Norwegian Meteorological Institute. Studies of wind driven current and storm response have been pursued through the participation in large project as MOMOP (MetOcean Modeling Project) where several graduate students were employed.

Flows over banks and canyons

Field measurements have established the existence of anticyclonic eddies over large banks as Haltenbanken on the shelf west of Norway. Water masses in these eddies water are trapped due to the bathymetric relief and circulate slowly in clockwise direction. This have a strong effect on the biological productivity and prevents eggs and larvae from drifting away. Model simulations with idealized bottom topography have demonstrated the formations of eddies and that the structure of the eddies depends on the directions and strength on the shelf edge current.

Vortex Dynamics

Numerical simulation of mesoscale and sub-mesoscale vortex motion in stratified fluids. Especially the interaction between topography and the vortex structures and the generation of internal waves are investigated. The study is also related to the work on flows over banks and canyons.

The project is funded by the Norwegian Research Council (NFR).

Picture: Dipole eddy approaching a step in bottom topography.

Destructive waves (Tsunamis) from slides and earthquakes

In this century three catatrophic events have occurred in Norway. In Loen, 1905, 1936 and Tafjord 1934 rock slides up to 1 mill cubic meter, from several hundre meter height, generated water waves in the fjord/lake with run-up 50-70 m above sea level. Tsunamis waves may also have been generated by the Storegga Slide, a submarine slide event on the continetal shelf west of Norway, about 8000 years BP. As part of the EU-funded research projects GITEC and GITEC-TWO (page in Norwegian), Genesis and Impact of Tsunamis on European Coasts, numerical models for generation and propagation of tsunami waves in European waters have been developed and tested by comparison with observations. Particular emphasis was devoted to applicability of models and recognition of general properties for wave propagation

The map to the right shows the locations of some Norwegian tsunami incidents. Circules () marks major disasters from the last centuries with more than 10 casualties. The square ()cooresponds to the Storeagga slide, while the triangles () represent a selection of smaller events. Many events are not included in the figure. In the last century, a total of about 180 persons have been killed by tsunamis in Norwegian waters.

Authors: <Bjørn Gjevik> bjorng@math.uio.no and <Halvard Moe> halvardm@math.uio.no