Comparison of radar and video observations of shallow water breaking waves

Simultaneous microwave and video measurements of shallow water breaking waves are presented. A comparison of the data from the two sensors shows that short-duration spikes in the measured X-band radar cross section are highly correlated with the presence of breaking waves in the video imagery. In addition, the radar backscatter from shallow water breaking events is responsible for 40% to 50% of the total cross section, which is a much larger contribution than typically observed for deepwater breaking events. Based on estimates of the area of individual breaking regions determined from digitized video images, the radar cross section per unit area of the turbulent breaking region is shown to be well approximated by a value of -1.9 dB at 31/spl deg/ grazing. Finally, there are some differences between the radar and video signals that suggest that microwave radar may be less sensitive than video techniques to relict foam not associated with active wave breaking. In general, the results indicate that radar is a very good detector of shallow water breaking waves and suggest that radar can be used for the measurement of the spatial and temporal variations of wave breaking.

[1]  David M. Farmer,et al.  Observations of the Scale and Occurrence of Breaking Surface Waves , 1999 .

[2]  Li Ding,et al.  Observations of Breaking Surface Wave Statistics , 1994 .

[3]  M. Long,et al.  On a two-scatterer theory of sea echo , 1974 .

[4]  V. V. Pustovoytenko,et al.  On polarization features of radio signals scattered from the sea surface at small grazing angles , 1976 .

[5]  R. Holman,et al.  Estimation of wave phase speed and nearshore bathymetry from video imagery , 2000 .

[6]  Yong Liu,et al.  Directional ocean wave measurements in a coastal setting using a focused array imaging radar , 1995, IEEE Transactions on Geoscience and Remote Sensing.

[7]  C. J. Zappa,et al.  Infrared remote sensing of breaking waves , 1997, Nature.

[8]  Paul S. Bell,et al.  Shallow water bathymetry derived from an analysis of X-band marine radar images of waves , 1999 .

[9]  David Lyzenga,et al.  Numerical calculations of radar scattering from sharply peaked ocean waves , 1998, IEEE Trans. Geosci. Remote. Sens..

[10]  Delwyn Moller,et al.  Directional ocean wave measurements in a coastal setting using a focused array imaging radar , 1995 .

[11]  J. A. McGregor,et al.  S band Doppler radar measurements of bathymetry, wave energy fluxes, and dissipation across an offshore bar , 1998 .

[12]  I. A. Svendsen.  Analysis of surf zone turbulence , 1987 .

[13]  R. Stephenson.  A and V , 1962, The British journal of ophthalmology.

[14]  Robert E. McIntosh,et al.  Measurement and classification of low-grazing-angle radar sea spikes , 1998 .

[15]  David T. Walker,et al.  Radar backscatter and surface roughness measurements for stationary breaking waves , 1996, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[16]  B. Lake,et al.  A deterministic, coherent, and dual-polarized laboratory study of microwave backscattering from water waves, Part I: Short gravity waves without wind , 1984, IEEE Journal of Oceanic Engineering.

[17]  Dennis B. Trizna,et al.  Errors in bathymetric retrievals using linear dispersion in 3-D FFT analysis of marine radar ocean wave imagery , 2001, IEEE Trans. Geosci. Remote. Sens..

[18]  A. L. Maffett,et al.  The Contribution of Wedge Scattering to the Radar Cross Section of the Ocean Surface , 1983, IEEE Transactions on Geoscience and Remote Sensing.

[19]  Anthony,et al.  The Generation of Longshore Currents on a Plane Beach , 2022 .

[20]  Robert E. McIntosh,et al.  Space-time properties of radar sea spikes and their relation to , 1998 .

[21]  I. D. Olin,et al.  Experimental study and theoretical model of high‐resolution radar backscatter from the sea , 1980 .

[22]  Richard J. Seymour,et al.  Detection of Breaking in a Deep Water Wave Record , 2002 .

[23]  Robert A. Holman,et al.  Quantification of sand bar morphology: A video technique based on wave dissipation , 1989 .

[24]  O. M. Phillips,et al.  Radar Returns from the Sea Surface—Bragg Scattering and Breaking Waves , 1988 .

[25]  Robert A. Shuchman,et al.  Analysis of scatterer motion effects in Marsen X band SAR imagery , 1983 .

[26]  Robert A. Holman,et al.  Generation of edge waves in shallow water , 1997 .

[27]  Martin Katzin,et al.  On the Mechanisms of Radar Sea Clutter , 1957, Proceedings of the IRE.

[28]  Andrew T. Jessup,et al.  Breaking waves affecting microwave backscatter: 1. Detection and verification , 1991 .

[29]  E. H. Fooks,et al.  On the microwave reflectivity of small-scale breaking water waves , 1985, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[30]  K. L. Beach,et al.  X band microwave backscattering from ocean waves , 1995 .

[31]  Andrew T. Jessup,et al.  Breaking waves affecting microwave backscatter: 2. Dependence on wind and wave conditions , 1991 .