Computer Modeling

Using different modeling tools Polytec’s MetOcean group can estimate near shore wave fields and forecast ocean surface waves. If large areas need to be studied direct observations are difficult. As an alternative Polytec employ modeling efforts using different ocean models. Wind fields over large areas can similarly be modeled using numerical weather models.

Furthermore Polytec has contributed to the development of a model which with a high degree of accuracy calculates ocean temperature at the sea floor in real time and also forecasts the future.

Wave Modeling

Polytec is using the wave models STWAVE and SWAN to estimate the near shore wave field. The forecast for ocean surface waves is based on methods similar to an atmospheric (weather) forecast, as we use a numerical wave model to predict the wave field at a limited numbers of grid points within a given region. Where the atmospheric forecast model is forced by the large scale weather system, the wave model requires information about the offshore waves, which, similar to the weather forecast, is obtained from a large scale (global) model. Based on offshore wave characteristics such as significant wave height, wave period and propagation direction, as well as the topographic features of the region, the model will calculate the wave field at all grid points using prognostic wave equations.

Pictures and animations

wave

Significant wave height of the Sletta region as estimated with STWAVE.

Ocean Modeling

When large areas are studied direct observations are not feasible. Instead a modeling effort must be made. At Polytec we use different ocean models, depending on the problem to be solved. For regional studies we apply the Regional Ocean Modeling System (ROMS) model that allows for coupling with both biological and sediment transport models. This is useful for many coastal purposes, e.g. studies of the ecosystems and fish resources.

In addition to the ROMS model Polytec has developed its own circulation model used to estimate the statistical flow field in fjords and other coastal areas. For large scale studies we apply the NEMO model.

Animations


Tidal forcing of the sea surface along the western part of Norway (southern Hordaland and northern Rogaland). The sea surface is gradually depressed in north and kept constant in south.


Tidal forcing of the sea surface for the Haugaland region The sea surface is oscillating in north and kept constant in south.


Evolution of the lightest waste particles released from a fish farm at different time steps. Green dots denote deposition at the sea floor

Atmospheric Modeling

The wind field over large areas is modeled using numerical weather models. Mesoscale models, such as the Weather Research and Forecasting model (WRF), are applied for Offshore Wind Energy applications. Coupled with programs that simulates the small scale flow (CFD and LES models) near the wind turbines provides detailed information about wind-turbine interaction.

Sea Floor Temperature Modeling

How much gas you can transport is related to the temperature of the gas, which in turn is related to the temperature of the sea. And here is the link to oceanography: If you want to know how much gas you can sell, you must know the temperature of the sea floor. There is a widespread misconception that the temperature of the sea bed is constant; it is not in any way correct for The North Sea.

Illustration of seasonal variations in bottom temperature in The North Sea. The model is 4 - dimensional (3 spatial coordinates x, y, z, and time). To visualize bottom temperature the upper water layers is removed in parts of the figure. The clock in the upper left corner shows the corresponding month.

Illustration of seasonal variations in bottom temperature in The North Sea. The model is 4 – dimensional (3 spatial coordinates x, y, z, and time). To visualize bottom temperature the upper water layers is removed in parts of the figure. The clock in the upper left corner shows the corresponding month.