Multifractal representation of breaking waves on the ocean surface

1994 ◽  
Vol 99 (C8) ◽  
pp. 16179 ◽  
Author(s):  
Bryan R. Kerman ◽  
Lucie Dernier
Keyword(s):  
Ocean Surface ◽  
Breaking Waves

Improving 3-D Variational Stereo Reconstruction of Oceanic Sea States by Camera Calibration Refinement

2013 ◽  
Author(s):  
Ping-Chang Shih ◽  
Guillermo Gallego ◽  
Anthony Yezzi ◽  
Francesco Fedele
Keyword(s):  
Error Function ◽  
Image Plane ◽  
Ocean Surface ◽  
Ocean Waves ◽  
Breaking Waves ◽  
Wave Climate ◽  
Climate Extreme ◽  
Projection Model ◽  
Refinement Procedure ◽  
Camera Parameters

Studies of wave climate, extreme ocean events, turbulence, and the energy dissipation of breaking and non-breaking waves are closely related to the measurements of the ocean surface. To gauge and analyze ocean waves on a computer, we reconstruct their 3-D model by utilizing the concepts of stereoscopic reconstruction and variational optimization. This technique requires a pair of calibrated cameras — cameras whose parameters are estimated for the mathematical projection model from space to an image plane — to take videos of the ocean surface as input. However, the accuracy of camera parameters, including the orientations and the positions of cameras as well as the internal specifications of optics elements, are subject to environmental factors and manual calibration errors. Because the errors of camera parameters magnify the errors of the 3-D reconstruction after projection, we propose a novel algorithm that refines camera parameters, thereby improving the accuracy of variational 3-D reconstruction. We design a multivariate error function that represents discrepancies between captured images and the reprojection of the reconstruction onto the images. As a result of the iteratively diminished error function, the camera parameters and the reconstruction of ocean waves evolve to optimal values. We demonstrate the success of our algorithm by comparing the reconstruction results with the refinement procedure to those without it and show improvements in the statistics and spectrum of the wave reconstruction after the refinement procedure.

scholarly journals On direct passive microwave remote sensing of sea spray aerosol production

2014 ◽  
Vol 14 (21) ◽  
pp. 11611-11631 ◽  
Author(s):  
I. B. Savelyev ◽  
M. D. Anguelova ◽  
G. M. Frick ◽  
D. J. Dowgiallo ◽  
P. A. Hwang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Brightness Temperature ◽  
Microwave Remote Sensing ◽  
Ocean Surface ◽  
Breaking Waves ◽  
Passive Microwave ◽  
Microwave Emission ◽  
Sea Spray ◽  
Sea Spray Aerosol ◽  
Microwave Emissions

Abstract. This study addresses and attempts to mitigate persistent uncertainty and scatter among existing approaches for determining the rate of sea spray aerosol production by breaking waves in the open ocean. The new approach proposed here utilizes passive microwave emissions from the ocean surface, which are known to be sensitive to surface roughness and foam. Direct, simultaneous, and collocated measurements of the aerosol production and microwave emissions were collected aboard the FLoating Instrument Platform (FLIP) in deep water ~ 150 km off the coast of California over a period of ~ 4 days. Vertical profiles of coarse-mode aerosol (0.25–23.5 μm) concentrations were measured with a forward-scattering spectrometer and converted to surface flux using dry deposition and vertical gradient methods. Back-trajectory analysis of eastern North Pacific meteorology verified the clean marine origin of the sampled air mass over at least 5 days prior to measurements. Vertical and horizontal polarization surface brightness temperature were measured with a microwave radiometer at 10.7 GHz frequency. Data analysis revealed a strong sensitivity of the brightness temperature polarization difference to the rate of aerosol production. An existing model of microwave emission from the ocean surface was used to determine the empirical relationship and to attribute its underlying physical basis to microwave emissions from surface roughness and foam within active and passive phases of breaking waves. A possibility of and initial steps towards satellite retrievals of the sea spray aerosol production are briefly discussed in concluding remarks.

Distribution of breaking waves at the ocean surface

Nature ◽  
2002 ◽  
Vol 417 (6884) ◽  
pp. 58-63 ◽  
Author(s):  
W. Kendall Melville ◽  
Peter Matusov
Keyword(s):  
Ocean Surface ◽  
Breaking Waves

scholarly journals On C-Band Quad-Polarized Synthetic Aperture Radar Properties of Ocean Surface Currents

2019 ◽  
Vol 11 (19) ◽  
pp. 2321 ◽  
Author(s):  
Shengren Fan ◽  
Vladimir Kudryavtsev ◽  
Biao Zhang ◽  
William Perrie ◽  
Bertrand Chapron ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Wave Breaking ◽  
Surface Current ◽  
Ocean Surface ◽  
Breaking Waves ◽  
Synthetic Aperture ◽  
Surface Currents ◽  
Sar Images ◽  
Current Signatures ◽  
Aperture Radar

We present new results for ocean surface current signatures in dual co- and cross-polarized synthetic aperture radar (SAR) images. C-band RADARSAT-2 quad-polarized SAR ocean scenes are decomposed into resonant Bragg scattering from regular (non-breaking) surface waves and scattering from breaking waves. Surface current signatures in dual co- and cross-polarized SAR images are confirmed to be governed by the modulations due to wave breaking. Due to their small relaxation scale, short Bragg waves are almost insensitive to surface currents. Remarkably, the contrast in sensitivity of the non-polarized contribution to dual co-polarized signals is found to largely exceed, by a factor of about 3, the contrast in sensitivity of the corresponding cross-polarized signals. A possible reason for this result is the co- and cross-polarized distinct scattering mechanisms from breaking waves: for the former, quasi-specular radar returns are dominant, whereas for the latter, quasi-resonant scattering from the rough breaking crests governs the backscatter intensity. Thus, the differing sensitivity can be related to distinct spectral intervals of breaking waves contributing to co- and cross-polarized scattering in the presence of surface currents. Accordingly, routinely observed current signatures in quad-polarized SAR images essentially originate from wave breaking modulations, and polarized contrasts can therefore help quantitatively retrieve the strength of surface current gradients.

Wave Breaking and Ocean Surface Layer Thermal Response

2004 ◽  
Vol 34 (3) ◽  
pp. 693-698 ◽  
Author(s):  
George Mellor ◽  
Alan Blumberg
Keyword(s):  
Surface Layer ◽  
Wave Breaking ◽  
Thermal Response ◽  
Ocean Surface ◽  
Breaking Waves ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Surface Temperatures ◽  
Charnock Constant ◽  
Ocean Surface Layer

Abstract The effect of breaking waves on ocean surface temperatures and surface boundary layer deepening is investigated. The modification of the Mellor–Yamada turbulence closure model by Craig and Banner and others to include surface wave breaking energetics reduces summertime surface temperatures when the surface layer is relatively shallow. The effect of the Charnock constant in the relevant drag coefficient relation is also studied.

scholarly journals On direct passive microwave remote sensing of sea spray aerosol production

2014 ◽  
Vol 14 (10) ◽  
pp. 15363-15417
Author(s):  
I. B. Savelyev ◽  
M. D. Anguelova ◽  
G. M. Frick ◽  
D. J. Dowgiallo ◽  
P. A. Hwang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Microwave Remote Sensing ◽  
Ocean Surface ◽  
Breaking Waves ◽  
Passive Microwave ◽  
Microwave Emission ◽  
Sea Spray ◽  
Back Trajectory ◽  
Sea Spray Aerosol ◽  
Microwave Emissions

Abstract. This study addresses and attempts to mitigate persistent uncertainty and scatter among existing approaches for determining the rate of sea spray aerosol production by breaking waves in the open ocean. The new approach proposed here utilizes passive microwave emissions from the ocean surface, which are known to be sensitive to surface roughness and foam. Direct, simultaneous, and collocated measurements of the aerosol production and microwave emissions were collected on-board FLoating Instrument Platform (FLIP) in deep water ∼150 km off the coast of California over a period of ∼4 days. Vertical profiles of coarse-mode aerosol (0.25–23.5 μm) concentrations were measured with a forward scattering spectrometer and converted to surface flux using dry deposition and vertical gradient methods. Back trajectory analysis of Northeast Pacific meteorology verified the clean marine origin of the sampled air mass over at least 5 days prior to measurements. Vertical and horizontal polarization surface brightness temperatures were measured with a microwave radiometer at 10.7 GHz frequency. Data analysis revealed a strong sensitivity of the brightness temperature polarization difference to the rate of aerosol production. An existing model of microwave emission from the ocean surface was used to determine the empirical relationship and to attribute its underlying physical basis to microwave emissions from surface roughness and foam within active and passive phases of breaking waves. A possibility of and initial steps towards satellite retrievals of the sea spray aerosol production are briefly discussed in concluding remarks.

scholarly journals Effects of foam on ocean surface microwave emission inferred from radiometric observations of reproducible breaking waves

2006 ◽  
Vol 44 (3) ◽  
pp. 569-583 ◽  
Author(s):  
S. Padmanabhan ◽  
S.C. Reising ◽  
W.E. Asher ◽  
L.A. Rose ◽  
P.W. Gaiser
Keyword(s):  
Ocean Surface ◽  
Breaking Waves ◽  
Microwave Emission

scholarly journals The Role of Whitecapping in Thickening the Ocean Surface Boundary Layer

2015 ◽  
Vol 45 (8) ◽  
pp. 2006-2024 ◽  
Author(s):  
Gregory P. Gerbi ◽  
Samuel E. Kastner ◽  
Genevieve Brett
Keyword(s):  
Boundary Layer ◽  
Initial Conditions ◽  
Ocean Surface ◽  
Breaking Waves ◽  
Length Scale ◽  
Surface Boundary ◽  
Transfer Velocity ◽  
Surface Boundary Layer ◽  
Turbulent Length Scale ◽  
Shear Production

AbstractThe effects of wind-driven whitecapping on the evolution of the ocean surface boundary layer are examined using an idealized one-dimensional Reynolds-averaged Navier–Stokes numerical model. Whitecapping is parameterized as a flux of turbulent kinetic energy through the sea surface and through an adjustment of the turbulent length scale. Simulations begin with a two-layer configuration and use a wind that ramps to a steady stress. This study finds that the boundary layer begins to thicken sooner in simulations with whitecapping than without because whitecapping introduces energy to the base of the boundary layer sooner than shear production does. Even in the presence of whitecapping, shear production becomes important for several hours, but then inertial oscillations cause shear production and whitecapping to alternate as the dominant energy sources for mixing. Details of these results are sensitive to initial and forcing conditions, particularly to the turbulent length scale imposed by breaking waves and the transfer velocity of energy from waves to turbulence. After 1–2 days of steady wind, the boundary layer in whitecapping simulations has thickened more than the boundary layer in simulations without whitecapping by about 10%–50%, depending on the forcing and initial conditions.

scholarly journals RESPONSE OF THE OCEAN SURFACE LAYER WITH BREAKING WAVES IN FETCH-LIMITED WIND CONDITIONS

2018 ◽  
Vol 74 (2) ◽  
pp. I_67-I_72 ◽  
Author(s):  
Ayumi SARUWATARI ◽  
Ryota SAKAGAWA ◽  
Junichi OTSUKA ◽  
Yasuyuki BABA ◽  
Teruhiro KUBO ◽  
...  
Keyword(s):  
Surface Layer ◽  
Ocean Surface ◽  
Breaking Waves ◽  
Ocean Surface Layer

scholarly journals Mapping Surface Currents and Waves with Interferometric Synthetic Aperture Radar in Coastal Waters: Observations of Wave Breaking in Swell-Dominant Conditions*

2013 ◽  
Vol 43 (3) ◽  
pp. 563-582 ◽  
Author(s):  
Paul A. Hwang ◽  
Jakov V. Toporkov ◽  
Mark A. Sletten ◽  
Steven P. Menk
Keyword(s):  
Surface Roughness ◽  
Wave Breaking ◽  
Wave Spectrum ◽  
Ocean Surface ◽  
Breaking Waves ◽  
Surface Velocity ◽  
Synthetic Aperture ◽  
Large Area ◽  
Length Scales ◽  
Spatial Coverage

Abstract Airborne and spaceborne interferometric synthetic aperture radars (InSARs) produce surface velocity measurements at very high spatial resolutions over a large area. The data allow construction of the velocity strain field for highlighting ocean surface processes such as wave breaking and rip currents. Also, coherence between signals from two interferometric channels is a descriptor of the correlation condition of the surface roughness that scatters back the radar signals and it is an indication of the ocean surface turbulence. Wave breaking is a major turbulence source causing surface roughness decorrelation, thus the coherence parameter serves as an independent means for detecting wave breaking. The results of breaking detection using roughness decorrelation and critical local acceleration are comparable. In this paper, the breaking fraction in swell-dominant mixed seas along a cross-shore transect is compared with several steepness parameters characterizing different length scales of surface waves. The highest correlation coefficient (from 0.90 to 0.99) is between the breaking fraction and windsea mean square slope contributed primarily by short waves. This result reinforces the previous field observations showing that the length scales of breaking waves are much shorter than the energetic components near the spectral peak, although dominant waves and the associated wave group modulation are important in triggering the breaking process. The large spatial coverage of airborne or spaceborne operation further offers the opportunity to investigate evolution of the surface wave spectrum in high spatial (subkilometer) resolution. This capability is very useful for monitoring the coastal wave and current environment.

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