Ocean modeling in Northern Norway: A tidal verification study

Abstract

The coast of Northern Norway has for the first time been modeled using an unstructured grid. The modeling is done using two separate grids of different resolution, and the model data is compared to measurements done along the coast to verify its performance for both the fine and coarse grid. The model is a 2-D depth integrated model of tidal circulation with bottom friction. The data have been analyzed and the model replicates the amplitude of the main tidal constituent M2 with an accuracy of about 95%, with the coarse grid surprisingly yielding slightly better results than the finer grid. The reason for this is believed to be because the southern boundary limit in the fine grid is located at an inconvenient area.

For the tidal currents modeled, the accuracy has been shown to be significantly lower. The magnitude of the velocity is in many cases correctly modeled, but with larger errors in the direction. M2 and N2 are generally modeled at slightly too high velocities while S2 and K1 are generally modeled at slightly too low velocities. The model impresses in the way that it in general perform just as good within a fjord or at other complex geometries, as it does close to the open sea. The model also perform equally good both at locations with strong and weak currents.