Abstract

The appearance of a horizontal array of linear lamps below the water surface when viewed from above is approximately in the form of contours of one component of the water surface slope. The degree of approximation is a fraction of one percent when this method is used to describe the slopes of a wind ruffled surface. An extension of the method to image both components of slope requires two arrays of lamps pulsed alternately and in synchronism with a fast camera.

© 2011 OSA

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. P. A. Hwang, D. B. Trizna, and J. Wu, “Spatial measurements of short wind waves using a scanning slope sensor,” Dyn. Atmos. Oceans 20(1-2), 1–23 (1993).
    [CrossRef]
  2. C. Cox and X. Zhang, “Optical methods for study of sea surface roughness and microscale turbulence,” in Proc. SPIE, Optical Technology in Fluid, Thermal, and Combustion Flow, III, Vol. 3172, S. S. Cha, J. D. Trolinger, and M. Kawahashi, ed. (1997).
  3. T. E. Hara, J. Bock, J. B. Edson, and W. R. McGillis, “Observation of short wind waves in coastal waters,” J. Phys. Oceanogr. 28(7), 1425–1438 (1998).
    [CrossRef]
  4. C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
    [CrossRef]
  5. F. M. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. 111(C6), C06005 (2006), doi:.
    [CrossRef]

2008

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

2006

F. M. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. 111(C6), C06005 (2006), doi:.
[CrossRef]

1998

T. E. Hara, J. Bock, J. B. Edson, and W. R. McGillis, “Observation of short wind waves in coastal waters,” J. Phys. Oceanogr. 28(7), 1425–1438 (1998).
[CrossRef]

1993

P. A. Hwang, D. B. Trizna, and J. Wu, “Spatial measurements of short wind waves using a scanning slope sensor,” Dyn. Atmos. Oceans 20(1-2), 1–23 (1993).
[CrossRef]

Banner, M. L.

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

Bock, J.

T. E. Hara, J. Bock, J. B. Edson, and W. R. McGillis, “Observation of short wind waves in coastal waters,” J. Phys. Oceanogr. 28(7), 1425–1438 (1998).
[CrossRef]

Bréon, F. M.

F. M. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. 111(C6), C06005 (2006), doi:.
[CrossRef]

Corrada-Emmanuel, A.

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

Edson, J. B.

T. E. Hara, J. Bock, J. B. Edson, and W. R. McGillis, “Observation of short wind waves in coastal waters,” J. Phys. Oceanogr. 28(7), 1425–1438 (1998).
[CrossRef]

Hara, T. E.

T. E. Hara, J. Bock, J. B. Edson, and W. R. McGillis, “Observation of short wind waves in coastal waters,” J. Phys. Oceanogr. 28(7), 1425–1438 (1998).
[CrossRef]

Henriot, N.

F. M. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. 111(C6), C06005 (2006), doi:.
[CrossRef]

Hwang, P. A.

P. A. Hwang, D. B. Trizna, and J. Wu, “Spatial measurements of short wind waves using a scanning slope sensor,” Dyn. Atmos. Oceans 20(1-2), 1–23 (1993).
[CrossRef]

McGillis, W. R.

T. E. Hara, J. Bock, J. B. Edson, and W. R. McGillis, “Observation of short wind waves in coastal waters,” J. Phys. Oceanogr. 28(7), 1425–1438 (1998).
[CrossRef]

Schultz, H.

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

Trizna, D. B.

P. A. Hwang, D. B. Trizna, and J. Wu, “Spatial measurements of short wind waves using a scanning slope sensor,” Dyn. Atmos. Oceans 20(1-2), 1–23 (1993).
[CrossRef]

Wolff, L. B.

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

Wu, J.

P. A. Hwang, D. B. Trizna, and J. Wu, “Spatial measurements of short wind waves using a scanning slope sensor,” Dyn. Atmos. Oceans 20(1-2), 1–23 (1993).
[CrossRef]

Yalcin, J.

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

Zappa, C. J.

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

Dyn. Atmos. Oceans

P. A. Hwang, D. B. Trizna, and J. Wu, “Spatial measurements of short wind waves using a scanning slope sensor,” Dyn. Atmos. Oceans 20(1-2), 1–23 (1993).
[CrossRef]

J. Geophys. Res.

F. M. Bréon and N. Henriot, “Spaceborne observations of ocean glint reflectance and modeling of wave slope distributions,” J. Geophys. Res. 111(C6), C06005 (2006), doi:.
[CrossRef]

J. Phys. Oceanogr.

T. E. Hara, J. Bock, J. B. Edson, and W. R. McGillis, “Observation of short wind waves in coastal waters,” J. Phys. Oceanogr. 28(7), 1425–1438 (1998).
[CrossRef]

Meas. Sci. Technol.

C. J. Zappa, M. L. Banner, H. Schultz, A. Corrada-Emmanuel, L. B. Wolff, and J. Yalcin, “Retrieval of short ocean wave slope using polarimetric imaging,” Meas. Sci. Technol. 19(5), 055503 (2008), doi:.
[CrossRef]

Other

C. Cox and X. Zhang, “Optical methods for study of sea surface roughness and microscale turbulence,” in Proc. SPIE, Optical Technology in Fluid, Thermal, and Combustion Flow, III, Vol. 3172, S. S. Cha, J. D. Trolinger, and M. Kawahashi, ed. (1997).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (4)

Fig. 1
Fig. 1

(a) A compressed image of 10 colored fluorescent lamps viewed through the still water surface in a laboratory wind/wave channel. Each lamp is 16 mm in diameter and 1.15 m long. They are separated by 74 mm center to center and are effectively 3 m below the water surface. (b) Part of an image of the lamps when a wind of 3.3 m/s (channel averaged) blows over the water surface. The x axis is parallel to the long axis of the image and the lamps are parallel to the y axis. The area of water surface shown is 176 mm by 80 mm (2816 by 1287 pixels). The camera, mounted with entrance pupil 1.8 m above the mean water surface, was pointed straight down. The photograph is one of 60 exposed in a burst one second long with exposure times of one millisecond. The image has been enhanced by a process that clears the background and identifies the color of individual contour stripes by averaging the color coordinates within each stripe. Stripes containing fewer than 128 pixels are ignored.

Fig. 2
Fig. 2

The geometry of refraction. (a) Plan view viewed from above. The origin of coordinates is centered in the entrance pupil of the camera, EP , here treated as negligible in size. An incident ray of light along I originating at the light source LS at S, is refracted at the water surface at p and continues along R to the camera. N is normal to the water surface at p. (b) Side view of three vertical planes respectively containing I , R and N . These three unit vectors are shown extended to illustrate end points on light source, entrance pupil and sea surface.

Fig. 3
Fig. 3

The relation of true contours to contour stripes. produced by a single lamp parallel to the y axis and centered below the camera (X = 0). The field of view of the camera is assumed to be 0.30 m by 0.24 m in the x and y dimensions respectively. (a) The mean value of each x-slope contour stripe produced by this lamp depends essentially only on x. (b) The uncertainties of contours expressed as the standard deviation of true values within each contour stripe found by the first method discussed in the text. (c) Standard deviation of probable uncertainties by the second method

Fig. 4
Fig. 4

Similar to Fig. 3 except that the single lamp source is now at X = 1.0 m.

Equations (5)

Equations on this page are rendered with MathJax. Learn more.

n   I         R   =   k   N
Ι = ( cos β  sin ϕ ,    sin β  sin ϕ ,  cos ϕ ) , R = ( cos γ  sin ψ ,     sin γ  sin ψ ,    cos ψ ) .
n  cos β  sin ϕ cos γ  sin ψ =   k  cos α  sin θ ,
n  sin β  sin ϕ sin γ  sin ψ = k  sin α  sin θ ,
n  cos ϕ cos ψ = k  cos θ .

Metrics