jonswappsd

[f, Syy, Hm0, fp, Tp, Tm01, Tm02] = jonswappsd(U10, F, fp, fs, N, gama, CalSpectralSP, dispout)

Description

Calculate JONSWAP spectrum (power spectral density), (Hasselmann et al. 1973)

Inputs

U10=10;

Wind velocity at 10 meter above surface level in (m/s)

F=10000;

Wind fetch length in (m)

fp=0.33;

Peak wave frequency (fp=1/Tp) in (Hz)

If CalSpectralSP=’yes’; then fp is calculated from U10 and F

gama=3.3;

Peak enhancement parameter (between 1 and 7)

fs=2;

Sampling frequency that data collected at in (Hz)

N=256;

Total number of points between 0 and fs that spectrum reports at is (N+1)

CalSpectralSP=’yes’;

Define to calculate spectral shape parameters or not (‘yes’: calculate, ‘no’: use given parameters by user)

dispout=’no’;

Define to display outputs or not (‘yes’: display, ‘no’: not display)

Outputs

f

Frequency (Hz)

Syy

Wave Energy Power Spectrum (m^2/Hz)

Hm0

Zero-Moment Wave Height (m)

fp

Peak wave frequency (Hz)

Tp

Peak wave period (second)

Tm01

Wave Period from m01 (second), Mean Wave Period

Tm02

Wave Period from m02 (second), Mean Zero Crossing Period

Examples

[f,Syy,Hm0,fp,Tp,Tm01,Tm02]=jonswappsd(10,10000,0.33,2,256,3.3,'yes','yes');

References

Hasselmann, K.; Barnett, T. P.; Bouws, E.; Carlson, H.; Cartwright, D. E.; Enke, K.; Ewing, J. A.; Gienapp, H.; Hasselmann, D. E.; Kruseman, P.; Meerbrug, A.; Muller, P.; Olbers, D. J.; Richter, K.; Sell, W., and Walden, H., (1973). Measurements of wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP). Deutsche Hydrographische Zeitschrift A80(12), 95p.