Between 12.11.2003 and 30.12.2003, bathymetric data was acquired in the Gulf of Cadiz during the R/V SONNE cruise SO175. The expedition aimed at a better understanding of the interaction between dynamic processes in a seismically active region with slow plate convergence. In the context of earthquake nucleation and subduction zone processes, the multidisciplinary research programme focused on physical and chemical behavior of sediments, pore water and fluids, exploration of the temperature field of the 1755 thrust earthquake event, the quantification of microbial activity, faunal assemblages, gas hydrates and the deployment of a long-term pressure probe. Bathymetric mapping with the multibeam echosounder (MBES) SIMRAD EM120 was utilized to image the nature of the Gibraltar Arc thrust wedge, a proposed subduction zone, and identify possible sampling sites. Sub-bottom profiling, seismic reflection imaging, heat flow measurements, the deployment of an Ocean Floor pore pressure system as well as video-guided systems and coring complemented the research programme.
CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval.
Description of the data source:
During the SO175 cruise, the hull-mounted multibeam echosounder (MBES) SIMRAD EM120 was utilized to perform bathymetric mapping. It allows to conduct surveys in water depths of up to 11,000 m. Two transducer arrays transmit frequency coded acoustic signals (11.25 to 12.6 kHz). Data acquisition is based on successive emission-reception cycles of the signal. While the emission beam has a dimension of 150° across and 2° along track, the reception is obtained from 191 overlapping beams with widths of 2° across and 20° along track. The beam footprint has a dimension of 2° by 2°. The beam spacing can be set to equidistant or equiangular. For further information on the system, consult: https://www.km.kongsberg.com/
During the cruise, an opening angle of 60-70° was used depending on the state of the sea, restricting the coverage to a maximum 14 km wide swath to gain a more continuous spacing of beams on the ocean floor. The spacing within these limits was controlled automatically by the echosounder system.
To convert the recorded travel times into water depth, several sound velocity profiles were obtained with the shipboard CTD, providing a correction for ray bending for each beam. Depth is estimated from each beam by using the two-way travel time and the known beam angle known, and taking into account the ray bending due to refraction in the water column by sound speed variations. Combining phase and amplitude provides measurement accuracy practically independent of the beam pointing angle.
Responsible person during this cruise / PI: Ingo Grevenmeyer (igrevemeyer@geomar.de) & Achim Kopf (akopf@marum.de)
Chief Scientist: Achim Kopf (akopf@marum.de)
CR: https://elib.suub.uni-bremen.de/ip/docs/ELibD1195_228.pdf
CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2003/20050152.htm
Between 12.11.2003 and 30.12.2003, bathymetric data was acquired in the Gulf of Cadiz during the R/V SONNE cruise SO175. The expedition aimed at a better understanding of the interaction between dynamic processes in a seismically active region with slow plate convergence. In the context of earthquake nucleation and subduction zone processes, the multidisciplinary research programme focused on physical and chemical behavior of sediments, pore water and fluids, exploration of the temperature field of the 1755 thrust earthquake event, the quantification of microbial activity, faunal assemblages, gas hydrates and the deployment of a long-term pressure probe. Bathymetric mapping with the multibeam echosounder (MBES) SIMRAD EM120 was utilized to image the nature of the Gibraltar Arc thrust wedge, a proposed subduction zone, and identify possible sampling sites. Sub-bottom profiling, seismic reflection imaging, heat flow measurements, the deployment of an Ocean Floor pore pressure system as well as video-guided systems and coring complemented the research programme.
CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval.
Description of the data source:
During the SO175 cruise, the hull-mounted multibeam echosounder (MBES) SIMRAD EM120 was utilized to perform bathymetric mapping. It allows to conduct surveys in water depths of up to 11,000 m. Two transducer arrays transmit frequency coded acoustic signals (11.25 to 12.6 kHz). Data acquisition is based on successive emission-reception cycles of the signal. While the emission beam has a dimension of 150° across and 2° along track, the reception is obtained from 191 overlapping beams with widths of 2° across and 20° along track. The beam footprint has a dimension of 2° by 2°. The beam spacing can be set to equidistant or equiangular. For further information on the system, consult: https://www.km.kongsberg.com/
During the cruise, an opening angle of 60-70° was used depending on the state of the sea, restricting the coverage to a maximum 14 km wide swath to gain a more continuous spacing of beams on the ocean floor. The spacing within these limits was controlled automatically by the echosounder system.
To convert the recorded travel times into water depth, several sound velocity profiles were obtained with the shipboard CTD, providing a correction for ray bending for each beam. Depth is estimated from each beam by using the two-way travel time and the known beam angle known, and taking into account the ray bending due to refraction in the water column by sound speed variations. Combining phase and amplitude is used to provide measurement accuracy practically independent of the beam pointing angle.
Responsible persons during this cruise / PI: Achim Kopf (akopf@marum.de) & Ingo Grevenmeyer (igrevemeyer@geomar.de)
Description of data processing:
Postprocessing and products were conducted by the Seafloor-Imaging & Mapping group of MARUM/FB5, responsible person: Paul Wintersteller (seafloor-imaging@marum.de). The open source software MB-System suite (Caress, D.W., and D.N. Chayes, MB-System Version 5.6, open source software distributed from the MBARI and L-DEO web sites, 2000-2012.) was utilized for this purpose. The data was corrected for the roll movement of the vessel. There were no tide, pitch and heave corrections. Using Mbeditviz, artefacts were cleaned manually. NetCDF (GMT) grids of the edited data as well as statistics were created with mbgrid. The published bathymetric grid of the EM120 during cruise SO175 has a resolution of 40 m. No total propagated uncertainty (TPU) has been calculated to gather vertical or horizontal accuracy. A higher resolution is, at least partly, achievable. All grids produced are retrievable through the PANGAEA database (www.pangaea.de).
Chief Scientist: Achim Kopf (akopf@marum.de)
CR: https://elib.suub.uni-bremen.de/ip/docs/ELibD1195_228.pdf
CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2003/20050152.htm
Raw data: not yet
Sediment echosounder data using Atlas Parasound P70 echosounder was recorded during SONNE cruise SO278, which took place between 12.10.2020 to 01.12.2020 bathymetry data based on multibeam echosounder (MBES) was recorded. The main objective of this cruise was to investigate the interactions between the seabed and ocean water in Greek waters, whereby the plate tectonic constellation of a broad collision zone represents a special tectonic drive. Investigations on mud volcanoes were carried out in four working areas: the Sartori mud volcano in the Calabrian Arc, the Cobblestone Area, the Olimpi Mud Volcano Field and the United Nation Ridge.
Description of data source:
During the SO278 cruise, the hull-mounted parametric sub-bottom profiler ATLAS PARASOUND P70 was used to conduct information about the sediment sub-surface and water column. Its function is based on the parametric effect of the non-linear relation of pressure and density during sonar propagation. The system utilizes two high-intensity waves with frequencies of 18-20 kHz (primary high frequency; PHF) and 22-24 kHz to create a secondary high (about 40-42 kHz) and secondary low frequency (SLF) of about 4 kHz. The SLF can record sub-bottom structures, whereas the PHF can image the water column and potential gas bubbles, plankton ,fish or nepheloid layers within. The transducer array has an opening angle of 4° by 5°, which corresponds to a footprint size of about 7% of the water depth. Data acquisition was performed using measured real-time values of surface sound velocity and a static sound velocity profile of 1500 m/s. Using the software ATLAS PARASTORE, data was displayed and stored as raw *.asd files and additional *.ps3 and auxiliary files for certain depth windows. The *.ps3 files were utilized for conversion to SEG-Y format and further processing using the software SeNT (developed by V. Spiess & H. Keil, MTU-GeoB) and Kingdom Suite.
For further information on the system, consult: https://epic.awi.de/id/eprint/26733/7/ATLAS_PARASOUND_2015-02.pdf
The sub-bottom profiler was operating almost continuously with a desired frequency of 4 kHz for SLF and a desired frequency of 18 kHz for PHF. Most of the time the system run as continuous wave for water column analyisis and simultaneously with the multibeam echosounder and provided the basis for gravity cores and heat flow measurements.
Chief Scientist: G. Bohrmann (gbohrmann@marum.de)
Swath sonar bathymetry data used for that dataset was recorded during RV SONNE cruise SO175 using Kongsberg EM 120 multibeam echosounder. The cruise took place between 12.11.2003 and 30.12.2003 in the Gulf of Cadiz. The expedition aimed at a better understanding of the interaction between dynamic processes in a seismically active region with slow plate convergence. Bathymetric mapping with the multibeam echosounder (MBES) SIMRAD EM120 was utilized to image the nature of the Gibraltar Arc thrust wedge, a proposed subduction zone, and to identify possible sampling sites. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval.
Description of the data source:
During the SO175 cruise, hull-mounted KONGSBERG EM120 multibeam ecosounder (MBES) was utilized to perform bathymetric mapping in middle to deep water depths. Two linear transducer arrays in a Mills Cross configuration transmit acoustic signals of a nominal sonar frequency of 12 kHz. With 191 beams, the emission cone has a dimension of max 140° across track and 1° along track, while the actual beam footprint is 2° by 2°. Depending on the roughness of the seafloor, the swath width on a flat bottom is maximum six times the water depth. For further information on the system, consult https://www.km.kongsberg.com/.
During the cruise, an opening angle of 135 - 140° was used depending on the state of the sea, though restricting the coverage of the swath to gain a more continuous spacing of beams on the ocean floor. The spacing within these limits was controlled automatically by the echosounder system.
To convert the recorded travel times into water depth, several sound velocity profiles were obtained with the shipboard CTD, providing a correction for ray bending for each beam. Responsible person during this cruise / PI: Achim Kopf (akopf@marum.de) & Ingo Grevenmeyer (igrevemeyer@geomar.de)
Description of data processing:
Postprocessing and products were conducted by the Seafloor-Imaging & Mapping group of MARUM/FB5, responsible person Paul Wintersteller (seafloor-imaging@marum.de). The open source software MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, https://www.mbari.org/products/research-software/mb-system, 2017) was utilized for this purpose.SVPs taken during this cruise were not sufficient enough to correct the recorded bathymetric data. Therefore sound velocity profiles were modelled using reference profiles from the world ocean atlas (S. Levitus, 1982),
extracted and calculated through the MB-System program mblevitus by
utilizing the DelGrosso equation. The surface sound speed has then been adapted according to the recordings during this cruise while there were no further corrections for roll, pitch and heave applied during postprocessing. A tide correction was applied, based on the Oregon State University (OSU) tidal prediction software (OTPS) that is retrievable through MB-System. CTD measurements during the cruise were sufficient to represent the changes in the sound velocity throughout the study area. Using Mbeditviz, artefacts were cleaned manually. NetCDF (GMT) grids of the edited data as well as statistics were created with mbgrid. The published bathymetric EM120 grid of the cruise SO175 has a resolution of 35 m. No total propagated uncertainty (TPU) has been calculated to gather vertical or horizontal accuracy. A higher resolution is, at least partly, achievable. The grid extended with _num represents a raster dataset with the statistical number of beams/depths taken into account to create the depth of the cell. The extended _sd -grid contains the standard deviation for each cell. The DTMs projections are given in Geographic coordinate system Lat/Lon; Geodetic Datum: WGS84. All grids produced are retrievable through the PANGAEA database (www.pangaea.de).
Chief Scientist: Achim Kopf (akopf@marum.de)
CR: https://elib.suub.uni-bremen.de/ip/docs/ELibD1195_228.pdf
CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2003/20050152.htm