French PIRATA cruises: acoustic data

Date 2020-06-12
Temporal extent 2015-03-18 -2020-03-20
Author(s) Habasque JérémieORCID1, Bourlès BernardORCID2, Bertrand ArnaudORCID3, Lebourges-Dhaussy AnneORCID1, Grelet JacquesORCID2, Rousselot Pierre2
Affiliation(s) 1 : Institut de Recherche pour le Développement, UMR LEMAR, IRD de Bretagne, BP70 29280 Plouzané, FRANCE
2 : Institut de Recherche pour le Développement, Unité de service Instrumentation, Moyens, Analytiques, Observatoires en Géophysique et Océanographie (IMAGO), Brest, France
3 : Institut de Recherche pour le Développement, MARBEC, Université de Montpellier, CNRS, IFREMER, IRD, Sète, FRANCE
DOI 10.17882/71379
Publisher SEANOE
Keyword(s) PIRATA, Acoustics
Abstract

This dataset contains acoustic data collected with scientific echosounders in the Gulf of Guinea during cruises performed onboard the French R/V Thalassa from 2015 to 2020 in the framework of the program «Prediction and Research moored Array in the Tropical Atlantic» (PIRATA ; Bourlès et al., 2009).

Licence CC-BY
Acknowledgements We want to acknowledge R/V Thalassa crews that made the surveys possible.
Sensor metadata

Continuous acoustic measurements were made with calibrated echosounders (Foote et al., 1987) Simrad EK60 (2015-2017) and EK80 (2018-2020) connected to hull-mounted (6m below the waterline) transducers operating at six frequencies: 18, 38, 70, 120, 200 and 333 kHz. Data were acquired at a typical vessel speed of 12 knots with an average ping interval of 3 s (2015-2018) or 9 s (2019-2020). The pulse length was set at 1024 µs for all frequencies and transmit powers were of 2000, 2000, 600, 200, 90 and 40 W for the six channels at 18, 38, 70, 120, 200 and 333 kHz, respectively. The water column was sampled down to depths of 1000, 800, 400, 250, 120 and 80 m, respectively for those channels.

Acoustic data were scrutinized, corrected and analysed using the “Movies3D” software developed at the “Institut Français de Recherche pour l'Exploitation de la Mer” (Ifremer; Trenkel et al., 2009) combined with the French “Institut de Recherche pour le Développement” (IRD) open source tool “Matecho” (Perrot et al., 2018), developed in MATLAB. Due to signal absorption and noise at station, only pings acquired at a speed higher than 1 knot were selected for the present study.

The near-field noise was removed (3 m deep from the transducer, that is 9 m deep from the surface) from the analysis; phantom bottom echoes were excluded and the bottom line was corrected manually. Echograms were cleaned by eliminating unwanted signals such as one impulsive noise, transient noise due to the interferences with other electronic devices or other sources. Background noise was estimated and subtracted using methods described by De Robertis and Higginbottom (2007). The weather was very quiet during these surveys, thus no further cleaning was necessary. The acoustic nautical area scattering coefficient (sA in m2 nmi-2 or NASC), an indicator of marine organisms biomass, and the acoustic volume backscattering strength (Sv in dB re 1m-1), an indicator of marine organisms density, were calculated. Data were echo-integrated onto 10 m high layers over 1 nmi ESDU (elementary sampling distance unit) with a -100 dB threshold, from 9 m down to 1000 m depth. The data provided are the results of the echointegration processing.

 

Sensors metadata and variables are described in the report "ICES. 2016. A metadata convention for processed acoustic data from active acoustic systems. Series of ICES Survey Protocols SISP 4-TG-AcMeta. 48 pp".

 

 

 

 

Data
File Size Format Processing Access
PIRATA FR25 echointegrated data from 18/03/2015 to 15/04/2015 106 MB NC, NetCDF Processed data Open access
PIRATA FR26 echointegrated data from 06/03/2016 to 12/04/2016 127 MB NC, NetCDF Processed data Open access
PIRATA FR27 echointegrated data from 26/02/2017 to 02/04/2017 126 MB NC, NetCDF Processed data Open access
PIRATA FR28 echointegrated data from 27/02/2018 to 05/04/2018 130 MB NC, NetCDF Processed data Open access
PIRATA FR29 echointegrated data from 28/02/2019 to 05/04/2019 127 MB NC, NetCDF Processed data Open access
PIRATA FR30 echointegrated data from 16/02/2020 to 31/03/2020 227 MB NC, NetCDF Processed data Open access
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How to cite 

Habasque Jérémie, Bourlès Bernard, Bertrand Arnaud, Lebourges-Dhaussy Anne, Grelet Jacques, Rousselot Pierre (2020). French PIRATA cruises: acoustic data. SEANOE. https://doi.org/10.17882/71379