Accuracy of Bathymetric Assessment by Locally Analyzing Radar Ocean Wave Imagery (February 2008)

Flampouris, Stylianos; Ziemer, F.; Seemann, J.

doi:10.1109/tgrs.2008.919687

Cited by 23 publications

(12 citation statements)

References 15 publications

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“…In the past, marine radar image sequences have been operationally used to determine two-dimensional wave spectra (Young et al 1985) and significant wave height (Nieto-Borge et al 2004). Furthermore, marine radars have been used to measure near-surface currents (Senet et al 2001;Trizna 2010), bathymetry (Bell 1999;Flampouris et al 2008), individual waves (Dankert and Rosenthal 2004), and wave groups (Dankert et al 2003a) and to detect ships (Vicen-Bueno et al 2011a). Marine radars are also useful for estimating wind speed and direction (Dankert et al 2003b;Dankert and Horstmann 2007).…”

Section: Introductionmentioning

confidence: 99%

Real-Time Ocean Wind Vector Retrieval from Marine Radar Image Sequences Acquired at Grazing Angle

Vicen-Bueno

Horstmann

Terril

et al. 2013

Journal of Atmospheric and Oceanic Technology

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This paper proposes a novel algorithm for retrieving the ocean wind vector from marine radar image sequences in real time. It is presented as an alternative to mitigate anemometer problems, such as blockage, shadowing, and turbulence. Since wind modifies the sea surface, the proposed algorithm is based on the dependence of the sea surface backscatter on wind direction and speed. This algorithm retrieves the wind vector using radar measurements in the range of 200-1500 m. Wind directions are retrieved from radar images integrated over time and smoothed (averaged) in space by searching for the maximum radar cross section in azimuth as the radar cross section is largest for upwind directions. Wind speeds are retrieved by an empirical third-order polynomial geophysical model function (GMF), which depends on the range distance in the upwind direction to a preselected intensity level and the intensity level. This GMF is approximated from a dataset of collocated in situ wind speed and radar measurements (;31 000 measurements, ;56 h). The algorithm is validated utilizing wind and radar measurements acquired on the Research Platform (R/P) FLIP (for Floating Instrumentation Platform) during the 13-day Office of Naval Research experiment on HighResolution Air-Sea Interaction (HiRes) in June 2010. Wind speeds ranged from 4 to 22 m s 21 . Once the proposed algorithm is tuned, standard deviations and biases of 148 and 218 for wind directions and of 0.8 and 20.1 m s 21 for wind speeds are observed, respectively. Additional studies of uncertainty and error of the retrieved wind speed are also reported.

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Section: Introductionmentioning

confidence: 99%

Real-Time Ocean Wind Vector Retrieval from Marine Radar Image Sequences Acquired at Grazing Angle

Vicen-Bueno

Horstmann

Terril

et al. 2013

Journal of Atmospheric and Oceanic Technology

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“…The echo-sounder's data covered partially the area imaged from the radar; all the available geo-located data are used for the validation. For the validation, a procedure similar to the validation of DiSC [14] is carried out. The bathymetry estimated from the radar analysis was compared to the survey data with the measured tidal level subtracted and the results plot against each other.…”

Section: Resultsmentioning

confidence: 99%

“…The analyzed radar data is a published dataset [14][15] composed by 12 radar image sequences, which consisted of 256 individual images with an interval of 1.8 s between successive images. The radar radius is approximately 1960 m and the radar spatial resolution of the Cartesian grid is 6.8 m. The main undersea illuminated geomorphological features are two crossing ship channels with minimum depth 3 m and maximum depth over 25 m and time varying shoals.…”

Section: Datamentioning

confidence: 99%

Analysis of nautical X-band radar images for the generation of bathymetric map by the NSP method

Serafino

Ludeno

Flampouris

et al. 2012

2012 IEEE International Geoscience and Remote Sensing Symposium

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This work presents the experimental validation of a novel data processing approach to estimate the local depth in a shallow coastal area starting from X-band radar data. The approach is based on the maximization of the Normalized Scalar Product (NSP) between the measured and the theoretical wave dispersion relations, which embed the dependence on the searched for parameters (current vector and depth). The use of NSP approach allows obtaining a high resolution spatial map of the investigated area and a thorough statistical analysis of this approach is carried out by comparison with the ground truth data collected by a multibeam echo-sounder. Finally, the accuracy of the NSP approach is compared with the one achieved by other methods and prove to provide better results.Index Terms-sea state monitoring, X-band radar data, shallow coastal areas, bathymetry

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“…Over the past few decades, there have been considerable efforts to utilize remote sensors to effectively sample this region [see Holman and Haller, 2013, for a review]. Parameters that are retrievable in a routine operational sense via radar remote sensing, include: bathymetry [e.g., Bell, 1999;Flampouris et al, 2008], wave directional distributions [e.g., Young et al, 1985;Frasier et al, 1995;Nieto Borge et al, 1999;Izquierdo and Guedes Soares, 2005], wave runup [Hasan and Takewaka, 2009], and surf zone morphology [e.g., Ruessink et al, 2002;McNinch, 2007]. In general, the retrieval of these parameters does not depend significantly on the details of the radar backscattering processes; hence, these were the first parameters to be operationalized.…”

Section: Introductionmentioning

confidence: 99%

Microwave backscattering from surf zone waves

Catalán

Haller

Plant

2014

J. Geophys. Res. Oceans

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The microwave backscatter properties of surf zone waves are analyzed using field observations. By utilizing a preexisting, independent, water surface discrimination technique, the microwave returns were extracted along individual waveforms and the data from shoaling (steepening) waves, surf zone breaking waves, and remnant foam were separated and quantified. In addition, a wave tracking analysis technique allows the returns to be examined on a wave-by-wave basis as individual waves progress through the shoaling zone and break on a nearshore sand bar. Normalized radar cross sections (NRCS), polarization ratios, Doppler spectra, and scatterer velocities were collected using a dual-polarized, X-band radar operating at lower grazing angles than previously reported (1 -3.5 ). The results indicate that the maximum NRCS levels are from the active breaking portions of the wave and were consistently about 220 dB, regardless of radar polarization, azimuth angle, wave height, or wind speed. In addition, breaking waves induce broadening of the Doppler spectra and mean scatterer velocities that correlate well with the carrier wave celerity. Analysis of the polarization ratios suggest that the active breaking portions of the wave are depolarized but that higher polarization ratios (>0 dB) are found on the leading edges shoreward of the active breaking portions of the waves, which indicates a clear distinction between two scattering regimes. These results are consistent with scattering from a very rough surface that is being mechanically generated by the breaking process, showing a good agreement with the expected grazing angle dependency of a Lambertian scatterer.

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Accuracy of Bathymetric Assessment by Locally Analyzing Radar Ocean Wave Imagery (February 2008)

Cited by 23 publications

References 15 publications

Real-Time Ocean Wind Vector Retrieval from Marine Radar Image Sequences Acquired at Grazing Angle

Real-Time Ocean Wind Vector Retrieval from Marine Radar Image Sequences Acquired at Grazing Angle

Analysis of nautical X-band radar images for the generation of bathymetric map by the NSP method

Microwave backscattering from surf zone waves

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