Mike 21BW - Large Breaking Waves causing High-Frequency Noise

Hi All

I'm currently running the following domain:
[b]Depth[/b]: -12 to +8m (Moving Shoreline + Breaking Waves)
[b]Grid[/b]: 2m x 2m
[b]Wave-series[/b]: 3.2m / 12 sec regular waves

Where the waves break a high-frequency noise start to appear. This eventually influences the wave breaking pattern, currents, etc. A quick Fast-Fourier Transformation revealed 6 and 6.7second waves to appear in this area (as shown in the picture). When using smaller waves (Hs < 2.0m) this problem becomes less prominent. Any ideas on how to reduce this high-frequency noise?

[img width=200 height=112]http://i.imgur.com/zHHIBIl.jpg[/img]

[i]The red-circled part on the chart represents 6.0 and 6.7sec waves and the yellow part the 12sec waves as expected.[/i]

Update: The 6-sec waves are some sort of reflection - another problem on it's own!

The chart below shows a more accurate FFT. The blue series indicates the energy spectrum at the wave-breaking line and the red series indicates the energy spectrum near the generation line.

[img width=200 height=134]http://i.imgur.com/fDca3Th.jpg[/img]

Update 2: The issue is probably fundamental: The wave series of: 3.2m / 12 sec  isn't a realistic case. The wave-period should be in the order of 15-18sec