2007 EuRad Conference: Speech on Oil Spectrum (ppt)

[object Object],Dr. Nicolas Pinel , Dr. Christophe Bourlier, Dr. Nicolas Déchamps IREENA Laboratory, Nantes, France E-mail: [email_address]

Introduction: Context ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],air oil sea scattered power incident power

Introduction: Objective ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],1. KA-1+GOA (Geometric Optics Approx.) + intuitive approach 2. SSA-1 (Small Slope Approximation) + intuitive approach MoM accelerated by PILE+FB+NSA [Déchamps et al., IEEE TAP, to be published] cf. oil slick detection

Outline ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],II.1. Natural interfaces: Statistical description  12  x  0 Height distribution: p h (  ) Height spectrum: S(k,  ) usually Gaussian Gaussian p h (  )   0 6  h 6  h x 2 x d L c M 2 M 1 x 1 W( x d ) x d x 1 L c  h 2 /e  h 2 Sea: much more complex…

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],II.1. Natural interfaces: Statistical description

[object Object],[object Object],II.2. Case of sea and oil slick surfaces + Sea surface ,[object Object],[object Object],[object Object],Capillarity waves: - Small roughness  h,s - Small correlation L c,s Several roughness scales  h,l  h,s L c,s L c,l

[object Object],[object Object],II.2. Case of sea and oil slick surfaces ,[object Object],[object Object],[object Object],Capillarity waves: - Smaller roughness  h,s - Small correlation L c,s air oil slick sea Yet damping dependent on various parameters ( layer thickness, … ) H  h,l  h,s L c,l + L c,s

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],II.3. Spectrum of clean and contaminated surfaces [1]: [Lombardini et al., JAOT, 1989] [2]: [Jenkins and Jacobs, PF, 1997]

[object Object],II.3. Spectrum of clean and contaminated surfaces Parameters relative to oil type:  D , E 0 Gravity waves: Weak damping Capillarity waves: Strong damping Retrieval from experiments in the Sicilian Channel and the Gulf of Maine [1]: [Lombardini et al., JAOT, 1989] [3]: [Pinel et al., TGRS, to be published, 03/2008]

[object Object],[object Object],[object Object],[object Object],II.3. Spectrum of clean and contaminated surfaces Confirmation of damping of small-scale heights Significant damping of slopes Clean sea water  D = 6 rad/s, E 0 = 9 mN/m  D =11 rad/s, E 0 =25 mN/m

[object Object],[object Object],[object Object],III. Case of sea and oil slick surfaces [4]: [Cox and Munk, JOSA, 1954] Higher damping for Lombardini et al. model Similar qualitative results Oil -> significant damping of slopes

Outline ,[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],IV. Application to oil slick radar detection

[object Object],[object Object],IV. Scattering from oil slicks on sea surfaces [5]: [Déchamps et al., IEEE TAP, to be published] Scattering from oil slicks: Low to moderate thicknesses => 2 identical surfaces Locally plane parallel interfaces => Substitution of the Fresnel reflection coefficient r 12 of the upper interface with the equivalent reflection coefficient r eq of the air/oil/sea system Application to an asymptotic method: KA-1+GOA, then SSA-1

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],IV. Numerical results u 10 = 5 m/s  i = 0 deg. H = {10; 1} mm Surface length L = 250  Sampling step  x =  /10  r sea = 70 + 41j  r oil = 2.25 + 0.01j f = 3 GHz =>

[object Object],IV. Numerical results Good agreement with reference method around the specular direction Sea (PILE+FB) Sea ( KA-1+GOA ) Oil+Sea (PILE+FB) Oil+Sea ( KA-1+GOA ) Oil (PILE+FB) Oil ( KA-1+GOA )

[object Object],IV. Numerical results Sea (PILE+FB) ooo Sea ( SSA-1 ) Oil+Sea (PILE+FB) +++ Oil+Sea ( SSA-1 ) Oil (PILE+FB) xxx Oil ( SSA-1 ) Very good agreement with reference method for all scattering angles

[object Object],IV. Numerical results Very good agreement with reference method for all scattering angles Sea (PILE+FB) ooo Sea (SSA-1 ) Oil+Sea (PILE+FB) +++ Oil+Sea ( SSA-1 ) Oil (PILE+FB) xxx Oil ( SSA-1 )

[object Object],IV. Numerical results [Pinel et al., TGRS, to be published, 03/2008] Sea (PILE+FB) ooo Sea ( SSA-1 ) Oil+Sea (PILE+FB) +++ Oil+Sea ( SSA-1 ) Oil (PILE+FB) xxx Oil ( SSA-1 ) Very good agreement with reference method for all scattering angles

Conclusions & Prospects ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],III. Case of sea and oil slick surfaces Stronger damping for Lombardini et al. model [4]: [Jenkins and Jacobs, Physics Fluids, 1997] [5]: [Pinel et al., TGRS, to be published, 03/2008] Parameters relative to oil type: 8 parameters (fluid mechanics)  D = 11 rad/s, E 0 = 25 mN/m Identical Gravity waves: Weak damping Capillarity waves: Strong damping

2007 EuRad Conference: Speech on Oil Spectrum (ppt)

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to 2007 EuRad Conference: Speech on Oil Spectrum (ppt)

Similar to 2007 EuRad Conference: Speech on Oil Spectrum (ppt) (20)

2007 EuRad Conference: Speech on Oil Spectrum (ppt)