seaswell1d

[fseparation, Hm0, Hm0sea, Hm0swell, Tp, Tpsea, Tpswell, m0, m0sea, m0swell, fp, Tm01, Tm02] = seaswell1d(f, Syy, fsepCalcMethod, fu, fmaxswell, fpminswell, Windvel, dispout)

Description

Partition (separate) wind sea from swell in a power spectral density using an one dimensional method

Inputs

f

Frequency (Hz)

Syy

Power spectral density (m^2/Hz)

fsepCalcMethod=’hwang’;

Wind sea swell separating calculation method

‘celerity’: using deep water wave celerity, ‘gilhousen’: Gilhousen and Hervey (2001),

‘hwang’: Hwang et al. (2012), ‘exact’: calculate exact value

fu=0.5;

An upper bound of a spectrum integration frequency (Hz)

fmaxswell=0.25;

Maximum frequency that swell can have, It is about 0.2 in Gulf of Mexico

fpminswell=0.1;

A lower bound of a spectrum (minimum frequency) that is used for Tpswell calculation

Windvel=10;

Wind velocity (m/s), only required for Gilhousen and Hervey (2001) method

dispout=’no’;

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

Outputs

fseparation

Wind sea and Swell Separation Frequency (Hz)

Hm0

Zero-Moment Wave Height (m)

Hm0sea

Sea Zero-Moment Wave Height (m)

Hm0swell

Swell Zero-Moment Wave Height (m)

Tp

Peak wave period (second)

Tpsea

Peak Sea period (second)

Tpswell

Peak Swell Period (second)

m0

Zero-Moment of the power spectral density (m^2)

m0sea

Zero-Moment of the wind sea spectrum (m^2)

m0swell

Zero-Moment of the swell spectrum (m^2)

fp

Peak wave frequency (Hz)

Tm01

Wave Period from m01 (second), Mean Wave Period

Tm02

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

Examples

N=2^11; %Total number of points
fs=2; %Sampling frequency
df=fs/N; %Frequency difference
f(:,1)=[0:df:fs/2]; %Frequency vector
f(1,1)=f(2,1)/2; %Assign temporarily non-zero value to fisrt element of f to prevent division by zero
SyySea=0.016.*9.81.^2./((2.*pi).^4.*(f.^5)).*exp(-1.25.*(0.33./f).^4); %Calculating Spectrum
SyySwell=0.016.*9.81.^2./((2.*pi).^4.*(f.^5)).*exp(-1.25.*(0.15./f).^4).*0.005; %Calculating Spectrum
Syy=SyySea+SyySwell;
f(1,1)=0;
Syy(1,1)=0;
[fseparation,Hm0,Hm0sea,Hm0swell,Tp,Tpsea,Tpswell,m0,m0sea,m0swell,fp,Tm01,Tm02]=seaswell1d(f,Syy,'exact',0.5,0.3,0,10,'yes');

References

Gilhousen, D. B., & Hervey, R. (2002). Improved estimates of swell from moored buoys. In Ocean Wave Measurement and Analysis (2001) (pp. 387-393).

Hwang, P. A., Ocampo-Torres, F. J., & García-Nava, H. (2012). Wind sea and swell separation of 1D wave spectrum by a spectrum integration method. Journal of Atmospheric and Oceanic Technology, 29(1), 116-128.