Citation:

PANGAEA.905794

Name: M74/3 raw data of EM120 multibeam echosounder (bathymetry & beam time)
Published: 2019-09-11
License: https://creativecommons.org/licenses/by/4.0/
Keywords: Bathymetry; EM120; hydroacoustics; Makran; seismics

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Abstract:

Between 30.10.2007 and 28.11.2007, bathymetric data was acquired on the continental margin of Pakistan in the Makran subduction zone during R/V METEOR cruise M74/3. This expedition builds on the findings of the previous cruise M74/2, which was dedicated to a systematic seep search in the working area, where several bubble flares, backscatter anomalies and distinct seismic records were detected by using sidescan sonar, multi-channel seismics and a sediment echosounder. These findings provided the basis for detailed surveying during the cruise M74/3. The multibeam echosounders (MBES) KONGSBERG SIMRAD EM120 and EM710 were utilized for extensive mapping of the working area, which is essential for most investigations. Furthermore, bathymetric mapping during M74/3 significantly increased the resolution of previous bathymetry grids and provided information for the deployment of the remotely operated vehicle (ROV) MARUM-QUEST. The ROV was utilized to map the seafloor, take samples at potential seep sites and deploy and recover autonomous tools, such as a bubble-meter and in-situ pore water sampler.

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 M74/3 cruise, the hull-mounted KONGSBERG SIMRAD EM120 multibeam ecosounder (MBES) was utilized to perform bathymetric mapping. The system covers full ocean depth and transmits a nominal sounding frequency of 12 kHz. It generates 191 beams with a 1°(Tx)/2°(Rx) and a maximum opening angle of 140°. For further information consult: https://epic.awi.de/26725/1/Kon2007a.pdf

The acquisition mode was set to obtain equally spaced soundings on the sea floor. Yaw movements of the ship were compensated automatically by transmitting the swath perpendicular to the track rather than to the ship's axis. The opening angle was limited by either the maximum angle possible, a maximum angle set or a maximum coverage on the sea floor. Those values were adjusted to the requirements of the special surveys in a range of 5.5 to 7 km. Where no data were available at all, the full opening angle of 140° was set. Ship speed varied between 2.5 kn and 12 kn. A sound velocity profile for the cruise was delivered during the first CTD station of the previous cruise M74/2. The depth of the water column is estimated through the two-way-travel time, beam angle and ray bending due to refraction in the water column by sound speed variations.

Systematically biased outer beams produced problems in areas with large overlap of parallel profiles. The applied sound velocity profile and a roll bias were tested as possible error sources, but no significant error was found. As the effect seems to be strongest on steep slopes, it might be a problem in yaw, which was not corrected for so far.

Responsible person during this cruise / PI: Markus Brüning

Chief Scientist: Gerhard Bohrmann (gbohrmann@marum.de)

CR: https://www.tib.eu/en/search/id/awi%3Adoi~10.2312%252Fcr_m74/

CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2007/20070155.htm

Keyword(s):

Bathymetry; EM120; hydroacoustics; Makran; seismics

Further details:

Bohrmann, Gerhard; Lahajnar, Niko; Gaye, Birgit; Spieß, Volkhard; Betzler, Christian (2010): Nitrogen Cycle, Cold Seeps, Carbonate Platform Development in the Northwestern Indian Ocean, Cruise No.74, August 31 - December 22, 2007. METEOR-Berichte, Leitstelle Meteor, Institut für Meereskunde der Universität Hamburg, 10-3, 212, https://doi.org/10.2312/cr_m74

Project(s):

Center for Marine Environmental Sciences (MARUM)

Coverage:

Median Latitude: 21.056300 * Median Longitude: 69.330600 * South-bound Latitude: 16.934300 * West-bound Longitude: 56.373900 * North-bound Latitude: 25.178300 * East-bound Longitude: 82.287300

Date/Time Start: 2007-10-30T00:00:00 * Date/Time End: 2007-11-28T00:00:00

Event(s):

M74/3-track * Latitude Start: 25.178300 * Longitude Start: 56.373900 * Latitude End: 16.934300 * Longitude End: 82.287300 * Date/Time Start: 2007-10-30T00:00:00 * Date/Time End: 2007-11-28T00:00:00 * Location: northwestern Indian Ocean * Campaign: * Basis: * Method/Device: Underway cruise track measurements (CT) * Comment: Fujayrah Harbor - Male

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator
1	File name	File name		Bohrmann, Gerhard
2	File format	File format		Bohrmann, Gerhard
3	File size	File size	kByte	Bohrmann, Gerhard
4	Uniform resource locator/link to file	URL file		Bohrmann, Gerhard

License:

Creative Commons Attribution 4.0 International (CC-BY-4.0)

Size:

1904 data points

Data

Download dataset as tab-delimited text — use the following character encoding:

1 File name	2 File format	3 File size [kByte]	4 URL file
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0004_20071101_150105_METEOR.all	ALL	12357	0004_20071101_150105_METEOR.all
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