Global Ensemble Ocean Wave Forecast System
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The Global Ensemble Ocean Wave Forecast System (GEOWaFS)
consists of the NOAA WAVEWATCH III™ (NWW3) wave model,
an ensemble of 11 different Global Forecast System (GFS) wind fields and an
initial wave field. The initial wave field adopts the same one used in the
operationally deterministic NWW3. Eleven individual wave fields are
generated using the NWW3 subject to the forcing of the 11 different wind
fields respectively.
Out of these 11 wind members, one member is the operationally deterministic
and the other 10 members are generated through introducing small, different
perturbations to the initial atmospheric field using the breeding method.
(Toth and Kalnay, 1993, 1997) This ensemble of the wind fields is
operationally generated for up to 126 prediction hours at the 00, 06, 12 and
18Z run cycles. In the GEOWaFS, we use each of the 11 wind fields as the
wind forcing to individually run the NWW3 to generate one member of wave
prediction. Thus, a total of 11 wave predictions are generated and they
constitute an ensemble for further statistical analysis.
Ensemble mean, spread and probability with various
thresholds are then calculated from the ensemble of these wave and sea
surface wind predictions. Wind speed, Significant Wave Height, and Peak
Wave Period are viewable by selecting from the following table.
Important Note: GEOWaFS uses version 2.22 of WAVEWATCH III™,
not the multigrid version.
The viewer controls allow you to select from the last 5 days
at the run times of 00Z, 06Z, 12Z, and 18Z. Spaghetti and Probability maps
include a control to select a threshold value for the selected parameter.
References
Toth, Z. and E. Kalnay (1993): "Ensemble Forecasting at NMC: The Generation
of Perturbations", Bulletin of the AMS, vol. 74, no. 12, pp. 2317-2330.
Toth, Z. and E. Kalnay (1997): "Ensemble Forecasting at NMC and the Breeding
Method", Monthly Weather Review, pp. 3297-3319.
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