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In June 1998, when
the ECMWF atmospheric model was coupled to the wave model, the
daily wave ensemble forecast become an operational product.
Alongside the deterministic forecast of wave fields on a 0.5
degrees irregular grid, a control forecast and 50 ensemble
forecasts were produced daily on a regular 1.5 degrees grid. The
fifty members of the ensemble are generated by perturbing the
initial atmospheric conditions by means of the most unstable
singular vectors. The initial wave fields are not perturbed,
however. In November 2000. model grid was changed to quasi-regular
1.0 degree latitude/longitude grid. Since September 2005, alongside
the deterministic forecast of wave fields on a 0.25 degrees
irregular grid, a control forecast and 50 ensemble forecasts are
produced daily on a regular 1.0 degrees grid. Also, in September
2005, the EPS global wave model spectral resolution was increased
to 24 directions and 30 frequencies.
In November 2006 ECMWF
upgraded its Ensemble Prediction System (EPS). In particular, the
forecast range was extended to 15 days using the EPS system with a
resolution of T399 L62 for day 1 to day 10 (leg 1) and T255 L62 for
T+246 to day 15 (leg 2). EPS also included two other
constant-resolution forecasts for calibration and validation
purposes ran one at T399 L62 and the other at T255 L62 for the full
forecast time range day 1 to day 15. The horizontal grid resolution
of wave fields was 100Km.
In January 2010 the EPS
Wave system was upgraded to a resolution of 0.5 degrees. The
horizontal grid resolution of wave fields is approximately
55Km.
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