Tide and surge models

Tide surge models can provide good approximations to the astronomical and surge tides in an area.

While not as good as predictions based on gauge data (model predictions accurate to better than 10 cm are possible at present), their geographical coverage is better, so predictions are available at high resolution (typically better than 50m, but limited by the resolution of the bathymetry).
Surge models are forced by tidal and wind data. Hindcast wind stress data from the ECMWF or NCEP reanalysis (extending back for decades)  can be used to represent historical surges and extract surge climatology. Surge elevations  at the model resolution can be produced for long periods and these can then be used to produce surge and extreme level statistics for a given location. It is also possible to use met forecasts to give surge predictions.
Models used include Telemac 2d and 3d, ADCIRC, and the Princeton Ocean Model, This model is driven by a global tidal model and ECMWF or NCEP reanalysis meteorological data. For example, we have used  Telemac2d with a finite element grid with resolution of about 200m near selected coastal sites, while the Princeton Ocean Model has been implemented with a typical resolution at the coast  of 1-5km. Model performance is optimised using feedback between the coastal tides and the boundary tides and bathymetry.

Wave models

For wave climatologies, wind data and data from global wave models can also be used to drive wave models at shelf and local scales. Such models may be coupled with tidal models. Models used include Swan and Tomawac (which couples directly with Telemac2d).

Wave devices maybe included in such models as an absorbtion / energy loss term at the locations of wave devices: this can be extended to enable a simple representation of wave arrays. A more realistic representation of wave devices represents a device in terms of absorption and radiation of energy; single devices have been included in standard wave models, and in diffraction models such as the refdif model.

Example of coastal coverage, NE Atlantic model

Local Models

Here, elevation and flow data from the large scale model is applied using innovative assimilation and correction techniques to drive small scale local models. Tidal and surge elevations accurate to better than 10cm are feasible using this technique.
Again, long term simulations are possible, to retrieve surge statistics for a given area; alternatively surge forecasting systems can be produced.

Prediction of surge residuals, Workington, 2002

Possible work
-2D and 3D models of flow and elevation, give elevation and depth average flows,
-Choice of tidal models
-Choice of wave models
--Tidal prediction based on model results
-Hindcasts of tide/surge elevations
-Wave prediction and wave climate
-analysis of wave data