It has been seen in some articles that SWAN simulated mean wave periods are low compared to buoy data. However, wave heights show good match. As both significant wave height and mean wave period are computed from wave spectra, then why is such discrepancy seen in simulated mean wave period?
The most common reason in most regions is that the coefficients related to wave dissipation due to the Whitecapping (Cds) are very high in the default swan setting, it is recommended to calibrate the SWAN model by decreasing the Cds coefficient and comparing the results against in situ measurements.
Anindita Patra regarding your question: why the average wave periods are low compared to the buoy data. it is absolutely normal if we consider all the output results in the statistical error analysis because the wave buoys are generally limited to 1.6s. the buoy cannot measure the wave period under 1.6s. however, the output of the wave periods given by SWAN depends on the frequency range selected in the command file. the selected frequency covers the gravitational wave from 0.033 hz to 1 hz.
Please try the simulation using a frequency range of [0.033hz-0.625hz] and compare the results against the buoy data.
I think there are questions not only to the model, but also to the measurement data. Which period was measured? zero-crossing? or 1d spectra ? or 2d directional spectra?
The model spectra is always rougher than the real spectra. integration errors...
I think wave height measurement is more simple than period.
we need to make sure that we are comparing the same periods.
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