FN Archimer Export Format PT J TI Seismic reflection imaging of shallow oceanographic structures BT AF PIETE, Helene MARIE, Louis MARSSET, Bruno THOMAS, Yannick GUTSCHER, Marc-Andre AS 1:1;2:2;3:3;4:3;5:1; FF 1:;2:PDG-ODE-LPO;3:PDG-REM-GM;4:PDG-REM-GM;5:; C1 Univ Brest, Lab Domaines Ocean, IUEM, F-29280 Plouzane, France. IFREMER, Ctr Brest, Lab Phys Oceans, F-29280 Plouzane, France. IFREMER, Ctr Brest, F-29280 Plouzane, France. C2 UBO, FRANCE IFREMER, FRANCE IFREMER, FRANCE SI BREST SE PDG-ODE-LPO PDG-REM-GM UBO IN WOS Ifremer jusqu'en 2018 copubli-france copubli-univ-france TC 14 TU Centre national de la recherche scientifique Institut de recherche pour le développement Institut français de recherche pour l'exploitation de la mer Service Hydrographique et Océanographique de la Marine Université de Bretagne Occidentale Université de Bretagne-Sud UR https://archimer.ifremer.fr/doc/00141/25193/23302.pdf LA English DT Article CR ASPEX5 CARAMBAR FROMVAR 2010 GO IFOSISMO BO Gwen Drez Le Suroît Côtes De La Manche Rrs Discovery DE ;seismic oceanography;seismic acquisition system;seasonal thermocline;Iroise Sea;Gulf of Cadiz;Florida Straits AB Multichannel seismic (MCS) reflection profiling can provide high lateral resolution images of deep ocean thermohaline fine structure. However, the shallowest layers of the water column (z < 150 m) have remained unexplored by this technique until recently. In order to explore the feasibility of shallow seismic oceanography (SO), we reprocessed and analyzed four multichannel seismic reflection sections featuring reflectors at depths between 10 and 150 m. The influence of the acquisition parameters was quantified. Seismic data processing dedicated to SO was also investigated. Conventional seismic acquisition systems were found to be ill-suited to the imaging of shallow oceanographic structures, because of a high antenna filter effect induced by large offsets and seismic trace lengths, and sources that typically cannot provide both a high level of emission and fine vertical resolution. We considered a test case, the imagery of the seasonal thermocline on the western Brittany continental shelf. New oceanographic data acquired in this area allowed simulation of the seismic acquisition. Sea trials of a specifically designed system were performed during the ASPEX survey, conducted in early summer 2012. The seismic device featured: (i) four seismic streamers, each consisting of six traces of 1.80 m; (ii) a 1000 J SIG sparker source, providing a 400 Hz signal with a level of emission of 205 dB re 1 μPa @ 1 m. This survey captured the 15 m thick, 30 m deep seasonal thermocline in unprecedented detail, showing images of vertical displacements most probably induced by internal waves PY 2013 PD MAY SO Journal Of Geophysical Research-oceans SN 0148-0027 PU Amer Geophysical Union VL 118 IS 5 UT 000324913700006 BP 2329 EP 2344 DI 10.1002/jgrc.20156 ID 25193 ER EF