|
The wave model at ECMWF is called the
“WAM”. It describes the rate of change of the
2-dimensional wave spectrum, in any water depth, caused by
advection, wind input, dissipation due to white capping and bottom
friction and non-linear wave interactions. It is set up so as
to allow the two-way interaction of wind and waves with the
atmospheric model. It is also incorporated in the EPS and seasonal
ensemble systems.
Radar altimeter wave-height data are
assimilated from satellites. Buoy wave data are not assimilated;
instead, they serve as an independent check on the quality of
modelled wave parameters. The propagation of swell in the wave
model is handled by a simple scheme that gives rise to a smoothing
of the wave field. At present the effects of surface currents on
the sea state are not taken into account. In particular areas, such
as the Gulf Stream or Agulhas current, the current effect may give
rise to localised changes of up to one metre in the wave
height.
The representation of the sea-ice fields is
not as accurate as would be needed to handle waves near the ice
edge. Due to the present model resolution, wave products near the
coasts and, to a lesser extent, in small enclosed basins (e.g. the
Baltic Sea) may be of lower quality than the open-ocean
products.
|
