User expectations for multibeam echo sounders backscatter strength data-looking back into the future

Lucieer, Vanessa; Roche, Marc; Degrendele, Koen; Malik, Mashkoor; Dolan, Margaret F.J.; Lamarche, Geoffroy

doi:10.1007/s11001-017-9316-5

Cited by 30 publications

(25 citation statements)

References 47 publications

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“…The backscatter time-series approach is quite different from backscatter mapping and seabed classification which require radiometric and geometric corrections. Indeed, beam-pattern correction and compensation of the backscatter angular dependency are necessary to provide an artefactfree final mosaic, allowing a classification of the acoustic information that can be correlated with the seabed geology and habitat types (see Lucieer et al 2017 for examples). In this study, i.e.…”

Section: Mbes Backscatter Acquisition and Processingmentioning

confidence: 99%

“…Significant differences (up to 5 dB) have been observed between mean backscatter levels measured from a common dataset processed by different backscatter processing software (Lucieer et al 2017). This inconsistency seriously hinders the integration within a same time series of backscatter mean levels and standard deviations calculated with different software.…”

Section: Mbes Backscatter Acquisition and Processingmentioning

confidence: 99%

“…Consequently, no level of reliability can be connected to the final time series of seafloor reflectivity values, used by geoscientists as a proxy to highlight significant changes of the seabed. Defining quality standards for MBES backscatter measurements, estimating accuracy level and evaluating quantitative capabilities to monitor the seabed integrity remain critical challenges (Lurton and Lamarche 2015;Lamarche and Lurton 2017;Lucieer et al 2017). …”

Section: Introductionmentioning

confidence: 99%

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Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Roche¹,

Degrendele²,

Vrignaud

et al. 2018

Mar Geophys Res

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The increased use of backscatter measurements in time series for environmental monitoring necessitates the comparability of individual results. With the current lack of pre-calibrated multibeam echosounder systems for absolute backscatter measurement, a pragmatic solution is the use of natural reference areas for ensuring regular assessment of the backscatter measurement repeatability. This method mainly relies on the assumption of a sufficiently stable reference area regarding its backscatter signature. The aptitude of a natural area to provide a stable and uniform backscatter response must be carefully considered and demonstrated by a sufficiently long time-series of measurements. Furthermore, this approach requires a strict control of the acquisition and processing parameters. If all these conditions are met, stability check and relative calibration of a system are possible by comparison with the averaged backscatter values for the area. Based on a common multibeam echosounder and sampling campaign completed by available bathymetric and backscatter time series, the suitability as a backscatter reference area of three different candidates was evaluated. Two among them, Carré Renard and Kwinte, prove to be excellent choices, while the third one, Western Solent, lacks sufficient data over time, but remains a valuable candidate. The case studies and the available backscatter data on these areas prove the applicability of this method. The expansion of the number of commonly used reference areas and the growth of the number of multibeam echosounder controlled thereon could greatly contribute to the further development of quantitative applications based on multibeam echosounder backscatter measurements.

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Section: Mbes Backscatter Acquisition and Processingmentioning

confidence: 99%

Section: Mbes Backscatter Acquisition and Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Roche¹,

Degrendele²,

Vrignaud

et al. 2018

Mar Geophys Res

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“…The development of new technologies and classification tools is in great demand from the industry, government agencies and scientific institutions. The increasing interest and necessity for seabed habitat mapping in marine spatial planning initiatives has forced the industry of sonar makers, software developers and scientific research institutions to invest in new technology capable of producing seabed classification over regional areas [6]. Fisheries, oil and gas exploration, offshore engineering, as well as shallow and deep sea mining are examples of industries that are requiring seabed classification to support environmental risk assessments and spatial planning [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Reef Mapping Using Different Seabed Automatic Classification Tools

et al. 2020

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There is a great demand to develop new acoustic techniques to efficiently map the seabed and automate the interpretation of acoustic, sedimentological, and imaging data sets, eliminating subjectivity. Here, we evaluate the potential, limitations and complementariety of distinct supervised and automatic classification techniques in the mapping of reefs by comparing these results with a reference map. The study was carried out in the Abrolhos Continental Shelf (Eastern Brazilian Continental Margin) using a multibeam echosounder and side scan sonar (SSS) dataset. Two automatic supervised techniques were applied. A reference map was derived by detailed manual interpretation carried out by three experts. The two supervised classification techniques were: benthic terrain modeler (BTM), a morphometric classification with focus on spatial analyses of the bathymetric grid derivatives, and object-based image analysis (OBIA), a segmentation applied to the backscatter data from the SSS mosaic. Both automatic techniques obtained similar values of reef coverage area, but overestimated the reef area when compared with the reference map. The agreement between BTM and OBIA results and the reference map was 69% and 67%, respectively. Disagreement was mainly due to quantity of reef (both methods over-estimated reef), while the disagreement in spatial allocation was relatively low, it indicates that both methods are reasonable representation of the spatial patterns of reef. Efficient mapping of reef in the wider area of the Abrolhos Continental Shelf will be best achieved by a further development of automatic methods tested against reference maps obained from representative areas of the seabed. By combining the results of the two automatic methods, it was possible to create an ensemble map, which achieved better agreement with the reference dataset.

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“…Environmental monitoring, based on the acquisition of MBES time series [31,32], requires investigating and understanding the repeatability and variability of the data. Besides the instrumental constraints (aimed at ensuring the consistency of measured data from different campaigns and/or sensors), multiple sources of environmental factors must be considered for their impact on the consistency and accuracy of backscatter data measurement.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Short-Term Tidal Variability of Multibeam Backscatter from Field Experiments on Different Seafloor Types

Montereale-Gavazzi

Roche²,

Degrendele³

et al. 2019

Geosciences

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Three experiments were conducted in the Belgian part of the North Sea to investigate short-term variation in seafloor backscatter strength (BS) obtained with multibeam echosounders (MBES). Measurements were acquired on predominantly gravelly (offshore) and sandy and muddy (nearshore) areas. Kongsberg EM3002 and EM2040 dual MBES were used to carry out repeated 300-kHz backscatter measurements over tidal cycles (~13 h). Measurements were analysed in complement to an array of ground-truth variables on sediment and current nature and dynamics. Seafloor and water-column sampling was used, as well as benthic landers equipped with different oceanographic sensors. Both angular response (AR) and mosaicked BS were derived. Results point at the high stability of the seafloor BS in the gravelly area (<0.5 dB variability at 45° incidence) and significant variability in the sandy and muddy areas with envelopes of variability >2 dB and 4 dB at 45° respectively. The high-frequency backscatter sensitivity and short-term variability are interpreted and discussed in the light of the available ground-truth data for the three experiments. The envelopes of variability differed considerably between areas and were driven either by external sources (not related to the seafloor sediment), or by intrinsic seafloor properties (typically for dynamic nearshore areas) or by a combination of both. More specifically, within the gravelly areas with a clear water mass, seafloor BS measurements where unambiguous and related directly to the water-sediment interface. Within the sandy nearshore area, the BS was shown to be strongly affected by roughness polarization processes, particularly due to along- and cross-shore current dynamics, which were responsible for the geometric reorganization of the morpho-sedimentary features. In the muddy nearshore area, the BS fluctuation was jointly driven by high-concentrated mud suspension dynamics, together with surficial substrate changes, as well as by water turbidity, increasing the transmission losses. Altogether, this shows that end-users and surveyors need to consider the complexity of the environment since its dynamics may have severe repercussions on the interpretation of BS maps and change-detection applications. Furthermore, the experimental observations revealed the sensitivity of high-frequency BS values to an array of specific configurations of the natural water-sediment interface which are of interest for monitoring applications elsewhere. This encourages the routine acquisition of different and concurrent environmental data together with MBES survey data. In view of promising advances in MBES absolute calibration allowing more straightforward data comparison, further investigations of the drivers of BS variability and sensitivity are required.

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User expectations for multibeam echo sounders backscatter strength data-looking back into the future

Cited by 30 publications

References 47 publications

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas

Reef Mapping Using Different Seabed Automatic Classification Tools

Insights into the Short-Term Tidal Variability of Multibeam Backscatter from Field Experiments on Different Seafloor Types

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