Backscattering from a sandy seabed measured by a calibrated multibeam echosounder in the 190–400 kHz frequency range

Wendelboe, Gorm

doi:10.1007/s11001-018-9350-y

Cited by 10 publications

(15 citation statements)

References 21 publications

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“…There is a need to better recognize and investigate the characteristics of backscatter in order to be able to use it for research in the most efficient way [23]. A few studies were conducted recently on calibrating MBESs in reference areas [13,[33][34][35]. The most common calibration methods are listed as follows:…”

Section: Models Classification and Calibrationmentioning

confidence: 99%

“…MBES measurement with corrected backscattering strength is generally sparse, although affordable [13]. Some companies (e.g., Kongsberg, NORBIT) provide calibration files based on tank measurements and, thus, offer the ability to record absolute backscattering strength values on the fly.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we also outline how we performed the calibration, which was one goal of the EU-funded project BONUS ECOMAP, where we used a calibrated NORBIT STX prototype sonar. Acoustic measurements of the seafloor with various incidence and corrected backscattering strength are extremely rare [13][14][15][16][17][18]. In this study, we intended to deliver a set of specific records of this kind, the first ones gathered in the Baltic Sea so far.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of Seafloor Acoustic Backscatter Angular Dependence at 150 kHz Using a Multibeam Echosounder

et al. 2021

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Acoustic seafloor measurements with multibeam echosounders (MBESs) are currently often used for submarine habitat mapping, but the MBESs are usually not acoustically calibrated for backscattering strength (BBS) and cannot be used to infer absolute seafloor angular dependence. We present a study outlining the calibration and showing absolute backscattering strength values measured at a frequency of 150 kHz at around 10–20 m water depth. After recording bathymetry, the co-registered backscattering strength was corrected for true incidence and footprint reverberation area on a rough and tilted seafloor. Finally, absolute backscattering strength angular response curves (ARCs) for several seafloor types were constructed after applying sonar backscattering strength calibration and specific water column absorption for 150 kHz correction. Thus, we inferred specific 150 kHz angular backscattering responses that can discriminate among very fine sand, sandy gravel, and gravelly sand, as well as between bare boulders and boulders partially overgrown by red algae, which was validated by video ground-truthing. In addition, we provide backscatter mosaics using our algorithm (BBS-Coder) to correct the angle varying gain (AVG). The results of the work are compared and discussed with the published results of BBS measurements in the 100–400 kHz frequency range. The presented results are valuable in extending the very sparse angular response curves gathered so far and could contribute to a better understanding of the dependence of backscattering on the type of bottom habitat and improve their acoustic classification.

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Section: Models Classification and Calibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measurement of Seafloor Acoustic Backscatter Angular Dependence at 150 kHz Using a Multibeam Echosounder

et al. 2021

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“…This allows us to perform relative calibration on the natural reference areas of known and stable acoustic properties. Other methods assume absolute calibration of MBES backscatter, by cross-calibration with calibrated devices, like a single-beam echosounder [17]. In this research, we conducted two separate surveys, using MBES uncalibrated in terms of acoustic backscatter.…”

Section: Introductionmentioning

confidence: 99%

Spatial and Temporal Changes of Tidal Inlet Using Object-Based Image Analysis of Multibeam Echosounder Measurements: A Case from the Lagoon of Venice, Italy

et al. 2020

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Scientific exploration of seabed substrata has significantly progressed in the last few years. Hydroacoustic methods of seafloor investigation, including multibeam echosounder measurements, allow us to map large areas of the seabed with unprecedented precision. Through time-series of hydroacoustic measurements, it was possible to determine areas with distinct characteristics in the inlets of the Lagoon of Venice, Italy. Their temporal variability was investigated. Monitoring the changes was particularly relevant, considering the presence at the channel inlets of mobile barriers of the Experimental Electromechanical Module (MoSE) project installed to protect the historical city of Venice from flooding. The detection of temporal and spatial changes was performed by comparing seafloor maps created using object-based image analysis and supervised classifiers. The analysis included extraction of 25 multibeam echosounder bathymetry and backscatter features. Their importance was estimated using an objective approach with two feature selection methods. Moreover, the study investigated how the accuracy of classification could be affected by the scale of object-based segmentation. The application of the classification method at the proper scale allowed us to observe habitat changes in the tidal inlet of the Venice Lagoon, showing that the sediment substrates located in the Chioggia inlet were subjected to very dynamic changes. In general, during the study period, the area was enriched in mixed and muddy sediments and was depleted in sandy deposits. This study presents a unique methodological approach to predictive seabed sediment composition mapping and change detection in a very shallow marine environment. A consistent, repeatable, logical site-specific workflow was designed, whose main assumptions could be applied to other seabed mapping case studies in both shallow and deep marine environments, all over the world.

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“…Conversely, these technologies have an unrealized potential to determine spatial and temporal dynamics of biologically impacted seafloor. Recent research activities to provide calibrated, multi-frequency acoustic scatter data from the seafloor [20][21][22] allow us to compare acoustic surveys undertaken at different seasons and with different systems and improve the spatial and temporal discrimination power of acoustic surveys. Improved knowledge on the impact of benthic life on seafloor properties would allow an improved understanding of the potential discrimination of acoustic techniques.…”

Section: Introductionmentioning

confidence: 99%

Impact of Sparse Benthic Life on Seafloor Roughness and High-Frequency Acoustic Scatter

et al. 2019

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Quantitative acoustic marine habitat mapping needs to consider the impact ofmacrobenthic organisms on backscatter data. However, the sensitivity of hydroacoustic systems toepibenthic life is poorly constrained. This study explores the impact of a benthic community withsparse abundance on seafloor microroughness and acoustic backscatter at a sandy seafloor in theGerman North Sea. A multibeam echo sounder survey was ground-truthed by landermeasurements combining a laser line scanner with sub-mm resolution and broad-band acoustictransducers. Biotic and abiotic features and spatial roughness parameters were determined by thelaser line scanner. At the same locations, acoustic backscatter was measured and compared with anacoustic scatter model utilizing the small-roughness perturbation approximation. Results of thelander experiments show that a coverage with epibenthic features of 1.6% increases seafloorroughness at spatial wavelengths between 0.005–0.03 m, increasing both spectral slope andintercept. Despite the fact that a strong impact on backscatter was predicted by the acoustic modelbased on measured roughness parameters, only a minor (1.1 dB) change of backscatter was actuallyobserved during both the lander experiments and the ship-based acoustic survey. The results of thisstudy indicate that benthic coverage of less than 1.6% is insufficient to be detected by currentacoustic remote sensing.

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Backscattering from a sandy seabed measured by a calibrated multibeam echosounder in the 190–400 kHz frequency range

Cited by 10 publications

References 21 publications

Measurement of Seafloor Acoustic Backscatter Angular Dependence at 150 kHz Using a Multibeam Echosounder

Measurement of Seafloor Acoustic Backscatter Angular Dependence at 150 kHz Using a Multibeam Echosounder

Spatial and Temporal Changes of Tidal Inlet Using Object-Based Image Analysis of Multibeam Echosounder Measurements: A Case from the Lagoon of Venice, Italy

Impact of Sparse Benthic Life on Seafloor Roughness and High-Frequency Acoustic Scatter

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