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Control of the repeatability of high frequency multibeam echosounder backscatter by using natural reference areas ArchiMer
Roche, Marc; Degrendele, Koen; Vrignaud, Christophe; Loyer, Sophie; Le Bas, Tim; Augustin, Jean-marie; Lurton, Xavier.
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...
Tipo: Text Palavras-chave: Multibeam echosounder; Seafloor backscatter; Repeatability; Calibration; Reference area; Monitoring.
Ano: 2018 URL: http://archimer.ifremer.fr/doc/00422/53384/54234.pdf
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Seafloor change detection using multibeam echosounder backscatter: case study on the Belgian part of the North Sea ArchiMer
Montereale-gavazzi, Giacomo; Roche, Marc; Lurton, Xavier; Degrendele, Koen; Terseleer, Nathan; Van Lancker, Vera.
To characterize seafloor substrate type, seabed mapping and particularly multibeam echosounding are increasingly used. Yet, the utilisation of repetitive MBES-borne backscatter surveys to monitor the environmental status of the seafloor remains limited. Often methodological frameworks are missing, and should comprise of a suite of change detection procedures, similarly to those developed in the terrestrial sciences. In this study, pre-, ensemble and post-classification approaches were tested on an eight km2 study site within a Habitat Directive Area in the Belgian part of the North Sea. In this area, gravel beds with epifaunal assemblages were observed. Flourishing of the fauna is constrained by overtopping with sand or increased turbidity levels, which...
Tipo: Text Palavras-chave: Multibeam; Seafloor backscatter; Change detection; Seafloor integrity; Marine Strategy Framework Directive; Reference calibration area.
Ano: 2018 URL: http://archimer.ifremer.fr/doc/00387/49807/50379.pdf
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Insights into the Short-Term Tidal Variability of Multibeam Backscatter from Field Experiments on Different Seafloor Types ArchiMer
Montereale-gavazzi, Giacomo; Roche, Marc; Degrendele, Koen; Lurton, Xavier; Terseleer, Nathan; Baeye, Matthias; Francken, Frederic; Van Lancker, Vera.
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 (similar to 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...
Tipo: Text Palavras-chave: Multibeam echosounder; Seafloor; Backscatter; Monitoring; Short-term variability; Sensitivity; High-frequency.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00485/59637/62660.pdf
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Results from the First Phase of the Seafloor Backscatter Processing Software Inter-Comparison Project ArchiMer
Malik, Mashkoor; Schimel, Alexandre C. G.; Masetti, Giuseppe; Roche, Marc; Le Deunf, Julian; Dolan, Margaret F.j.; Beaudoin, Jonathan; Augustin, Jean-marie; Hamilton, Travis; Parnum, Iain.
Seafloor backscatter mosaics are now routinely produced from multibeam echosounder data and used in a wide range of marine applications. However, large differences (>5 dB) can often be observed between the mosaics produced by different software packages processing the same dataset. Without transparency of the processing pipeline and the lack of consistency between software packages raises concerns about the validity of the final results. To recognize the source(s) of inconsistency between software, it is necessary to understand at which stage(s) of the data processing chain the differences become substantial. To this end, willing commercial and academic software developers were invited to generate intermediate processed backscatter results from a common...
Tipo: Text Palavras-chave: Acoustic backscatter processing; Multibeam Echo Sounders; Seafloor mapping.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00599/71133/69448.pdf
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