Model upgrades

A new single model configuration (AUSWAVE-G3) will replace the legacy global (AUSWAVE-G) and regional (AUSWAVE-R) systems since 04 Aug 2022  

Features of this upgrade include:

• Incorporating the latest version of Wavewatch III® (WW3) - version 6.0.7;
• Spherical Multiple Cell Grid with two tier refinement
  • 12km and 6km at low latitudes, and
  • 25km and 12km at high latitudes beyond 55oN and 55oS in the zonal (east-west) direction, 12km and 6km remain in the meridional (northsouth) direction);
• An increase in spectral resolution from 24 directions and 25 frequency bins to 30 directions and 28 frequency bins;
• Interpolation from SMC grids to regular grids at 12.5km for the global domain and 6.25km for the Australian domain;
• Newly the runs at 6 and 18 UTC are provided too but with shorter forecast length (up to +156 hours);

The METNO changes the model from WAM to WAVEWATCHIII v 6.07. since 0Z run on 03 Oct 2023 

Model description can be found in https://marine.met.no/models

The new version of the WAM code is Cycle 4.7 (before it was Cycle 4.5) has been implemented since 12Z run on 10 Nov 2021 

The main differences with respect to the previous version are updated physics, propagation of waves under sea ice, and a correction for the unrealistic growth of the waves in very high winds. Other differences are: a reformulation of the mean wavenumber and mean frequency as well as a new formulation for detecting freak waves. Also, wave refraction by bottom topography is included which was absent in the previous set-up.

• Model Name and version: GFS-Wave, WAVEWATCH III v6.07
• Resolution changed to 0.25 degrees
• Lead time length changed to +384h
  • Step frequency: 1 (0:120), 3 (123:384)

The change has been applied since 12Z run on 10 Jan 2023 :

• Resolution changed to 0.1 degrees
• Lead time length changed to +180h

NZMS data after the upgrade on 14-09-2020 contained grid with 1441 longitude points from 0 to 359.9 degrees instead of the intended 1440 points from 0 to 359.75 degrees corresponding exactly to  0.25 degrees resolution. The extra grid point made the resolution slightly less than 0.25. The fix has been applied since 0Z, 11-06-2021 run.

• Resolution changed to 0.25 degrees 
• Lead time length changed to +168h

Topography field has been updated.  It should improve forecasts near coast and islands.