Sea surface omnidirectional motion spectrum model
seaSpectrum object creates a spectrum model for use in the
SpectralModel property of the
seaspect = seaSpectrum
seaspect with default property
values. The default sea surface spectrum and spreading function are based on the
Elfouhaily model. The Elfouhaily model is an omnidirectional and wind-dependent spectrum.
The wave spectrum consists of the frequency spectrum and angular spreading function. The
spreading function is symmetric about the wind direction and has both wave number and wind
seaspect = seaSpectrum(
Name = Value)
seaSpectrum object with the specified property
Name set to the specified
Value. You can
specify additional name-value pair arguments in any order as (
NameN = ValueN).
SpectrumSource — Source of omnidirectional spectrum
'Auto' (default) |
Source of the omnidirectional wave spectrum, specified as
'Auto'creates an Elfouhaily sea spectrum. The object offers properties that tailor the Elfouhaily sea spectrum.
'Custom'allows you to specify the omnidirectional wave spectrum using the
Resolution — Sea surface resolution
8 (default) | positive scalar | 1-by-2 vector of positive values
Sea surface resolution, specified as a positive scalar or as a 1-by-2 vector of
positive values. The resolution vector takes the form
resolutionY denote the resolution in the x- and
y- directions, respectively. If the resolution is a scalar, the
x-resolution and y-resolution is the
The sea surface physical length is calculated as the difference of the limits of the
Boundary property of the
object in the x and y dimensions. The sea surface
length has samples spaced by the
Resolution property. The length
should not be set below 0.02 m as the wave motion below 0.02 m is minimal. Units are in
CustomSpectrum — Omnidirectional wave spectrum
Omnidirectional wave spectrum, specified as an M-by-N matrix. M and N dictate the inverse fast Fourier transfer (IFFT) length when returning the elevation data of the sea surface in the x and y dimensions, respectively.
The resolution for the custom case is calculated as Resolution =
surface length is the sea surface physical length, calculated as
the difference of the limits of the
Boundary property of the
the x and y dimensions.
To enable this property, set the value of the
WaveVectorSpacing — Wave vector domain spacing
(default) | positive scalar | 1-by-2 real-valued vector
Positive wavevector domain spacing, specified as a scalar or a 1-by-2 dimension
ky]. This property represents the wavevector spacing in the
x and y dimensions, respectively. Units are
radians/meter. This value is typically set as WaveVectorSpacing <=
2*pi/surface length where surface length is the
sea surface physical length, calculated as the difference of the limits of the
Boundary property on the
the x and y dimensions.
To enable this property, set the
SpectrumSource property to
Create Surface from Sea Spectrum
Create a 1024-by-1024 m square sea surface. Assume an NRL reflectivity model for a high sea state 6 with a wind speed of about 20 m/s and a fetch of 250 km. Set
UseOcclusion in the
Create a radar scenario.
scene = radarScenario;
Model the reflectivity using the NRL model.
refl = surfaceReflectivitySea(Model = 'NRL',SeaState = 6, ... Polarization = 'V')
refl = surfaceReflectivitySea with properties: Model: 'NRL' SeaState: 6 Polarization: 'V' Speckle: 'None'
rng(2033) spec = seaSpectrum(Resolution = 2); bnds = [0 1024; 0 1024]; srf = seaSurface(scene,Boundary = bnds, ... WindSpeed = 20,Fetch = 250e3, ... SpectralModel = spec); mgr = scene.SurfaceManager; mgr.UseOcclusion = false
mgr = SurfaceManager with properties: UseOcclusion: 0 Surfaces: [1x1 radar.scenario.SeaSurface]
x = linspace(srf.Boundary(1,1),srf.Boundary(1,2),1000); y = linspace(srf.Boundary(2,1),srf.Boundary(2,2),1000); [X,Y] = meshgrid(x,y); X1 = X(:)'; Y1 = Y(:)'; hts = height(srf,[Y1;X1]); hts = reshape(hts,length(x),length(y)); surf(x,y,hts) axis equal shading interp ylabel('X (m)') xlabel('Y (m)') zlabel('Height (m)')
Sea Surface with Custom Wave Spectrum
Create a square sea surface with a custom wave spectrum. Import a JONSWAP wave spectrum with a moderate sea state. The spectrum is a 64-by-64 matrix with a physical length of 512 m and a resolution of 2 m.
scene = radarScenario(IsEarthCentered = false);
Add a sea surface to the scene with a custom spectrum
load('jonswap.mat'); spec = seaSpectrum(SpectrumSource = 'Custom', Resolution = 2, ... CustomSpectrum = Psi,WaveVectorSpacing = 2*pi/512)
spec = seaSpectrum with properties: SpectrumSource: 'Custom' CustomSpectrum: [64x64 double] WaveVectorSpacing: 0.0123
srf = seaSurface(scene,Boundary = [-256 256; -256 256], ... SpectralModel = spec)
srf = SeaSurface with properties: WindSpeed: 10 WindDirection: 0 Fetch: Inf SpectralModel: [1x1 seaSpectrum] RadarReflectivity: [1x1 surfaceReflectivitySea] ReflectivityMap: 1 ReferenceHeight: 0 Boundary: [2x2 double]
x = linspace(srf.Boundary(2,1),srf.Boundary(2,2),1000); y = linspace(srf.Boundary(1,1),srf.Boundary(1,2),1000); [X,Y] = meshgrid(x,y); X1 = X(:)'; Y1 = Y(:)'; hts = height(srf,[Y1;X1]); hts = reshape(hts,length(x),length(y)); surf(x,y,hts) axis equal shading interp ylabel('X (m)') xlabel('Y (m)') zlabel('Height (m)')
 Elfouhaily, T., B. Chapron, K. Katsaros, and D. Vandemark. "A Unified Directional Spectrum for Long and Short Wind-Driven Waves." Journal of Geophysical Research: Oceans 102, no. C7 (July 15, 1997): 15781-96. https://doi.org/10.1029/97JC00467
 Tessendorf, Jerry . "Simulating Ocean Water." Presented at SigGraph, 1999 - 2004.
Introduced in R2022a