CHARACTERISTICS

DESCRIPTION

Identification

HYPAS
Model originators : Dr. H Günther en Dr. W. Rosenthal
GKSS Forschungszentrum GmbH,
Institut für Physik (Deutschland)
Model operator : MUMM

Scope

The model predicts 2D wave spectra along the Belgian coast.

Conceptual background

The Hypas model is a second-generation wave model which computes at each grid point and at each time step the whole wave spectrum taking into account the wave generation by atmospheric energy input, energy dissipation by bottom friction and wave break, wave propagation and non linear interaction between various wave components.

This model has a spatial resolution of 50 km * 50 km. In order to account for the complex bathymetry in the southern North Sea, a high-resolution model (10 km * 10 km) is coupled to the coarse grid model through two open boundaries.

Inputs

Bathymetrical data and atmospheric data (wind fields over the whole coarse grid at 10 m height from Bracknell).

Geographical coverage

The Hypas wave model is applied for a domain covering the entire North Sea.

The grids used are stereographic grids.

The corners of the coarse HYPAS grid are

Left up (- 13.853°W, 68.978°N)
Left down (-4.099°W,48.226°N)
Right up (18.707°E, 69.511°N)
Right down (11.483°E,48.458°N)

The corners of the fine HYPAS grid are

Left up (0.711°W, 52.08°N)
Left down (0.962°W, 49.904°N)
Right up (4.284°O, 52.174°N)
Right down (4.326°O, 49.993°N)

Outputs

For each grid point and for each time step (3 hours), HYPAS gives the fully 2D wave spectrum. From this spectrum all kind of integrated parameters can be calculated.

The post processing provides only

— time series (each 3 hours) of various wave parameters at selected stations

— fields of significant wave height and low frequency energy on the whole domain and the two girds each 3 hours

— wave spectra (frequency and direction) at selected stations each 3 hours

Validation

In 1992, studies of D.Van den Eynde showed

bias(Hs)=13.6cm; S.I.(Hs)=31.8%;
bias(Tm)=0.23s; S.I.(Tm)=26.3%.

and studies of F.Ovidio et al. showed in 1994:

bias(Hs-altimeter)=42cm; S.I.(Hs-altimeter)=38%;
bias(Hs-buoy)=17.3cm; S.I.(Hs-buoy)=36%

where Hs is the significant height and Tm the mean period.

Present field of application

The model gives wave characteristics over the whole North Sea. It will serve as a management tool for ship routing towards the Belgian sea harbours through the shallow waters of the southern Bight of the North Sea.

possible complementary use

It could be used in coupling with the oil spill model SLICK and the hydrodynamic model OPTOS.

Present limitations, future needs and possible development

The model itself doesn't take into account refraction or changes of the depth due to tidal elevation

Reference of representative publication

Günther & Rosenthal, 1985. The hybrid parametrical (HYPAS) wave model. In: Ocean wave modelling, Swamp group. Plenum Press, New Yorl, 211-214.

Günther, H., W. Rosenthal, T.J. Weare, B.A. Worthington, K. Hasselmann & J.A. Ewing, 1979. A hybrid parametrical wave prediction. Journal of Geophysical Research, 84, 5752-5738.

Hermans, I., 1989. Wave modeling at the Belgian coast by means of the HYPAS model. In: Progress in Belgian Oceanographic Research 1989, ed. G. Pichot, DPWB-MUMM, 75-110.

Ovidio, F., J.-R. Bidlot, D. Van den Eynde, W. Luo and J. Monbaliu, 1994. Validation of the second generation wave forecasting model mu-WAVE: comparison with ERS-1, buoy data and WAM forecasts. In: Proceedings of the First ERS-1 Pilot Project Workshop, Toledo, Spain, 22-24 June 1994, ESA SP-365, 21-28.