DOI: 10.1594/pangaea.902390
title: Gridded bathymetry from EM120 multibeam echosounder of RV METEOR cruise M70/3

description: Between 26.11.2006 and 08.12.2006, bathymetric data was acquired in the Eastern Mediterranean Sea during the R/V METEOR cruise M70/3, which was aimed at key processes at cold seeps in the Anaximander Mountains south of Turkey. The cruise addressed factors controlling fluid escape at cold seeps, precipitates and their mineral composition, the quantification of gas and gas hydrates that exist in the sediments or escape as gas bubbles into the water column, as well as seep-related ecology. The multibeam echosounder (MBES) SIMRAD EM120 was utilized to survey the working area and produce detailed bathymetric maps, specifically of the mud volcanoes. Furthermore, hydroacoustic mapping provided the basis for dive planning of the Remotely Operated Vehicle (ROV) MARUM-QUEST and flare-imaging profiles with the sub-bottom profiler PARASOUND. Further sampling was carried out with the moving lander MOVE, an Autoclave tool and several sediment coring devices. 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 M70/3 cruise, the hull-mounted SIMRAD 120 multibeam ecosounder (MBES) was utilized to perform bathymetric mapping, which transmits a nominal sounding frequency of 12 kHz. During the cruise, the opening angle of the multibeam echosounder was set to 140° (for one profile 150°). The 191 generated beams were set to yield an equidistant spacing on the seafloor and yaw correction was applied. For further information, contact: https://www.kongsberg.com/maritime/support/ During large scale surveys, the ship speed was 8 knots. For detailed surveying of mud volcanoes, the beam angle was adjusted to cover a swath width of about one nautical mile on the seafloor and ship speed was reduced to 5 knots. The EM120 was running during station work and ROV dives as long as it did not disturb the flare detection of the sub-bottom profiler. A sound velocity profile generated from the Levitus database was applied. 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. Responsible person during this cruise / PI: Markus Brüning Description of data processing: On board R/V METEOR, the IFREMER CARAIBES software served as a first processing tool for the SIMRAD data. Onshore, 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 5.3, open source software distributed from the MBARI and L-DEO web sites, 2000-2012.) was utilized for this purpose. There were no tide, roll, 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 cruise M70/3 has a resolution of 50 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. All grids produced are retrievable through the PANGAEA database (www.pangaea.de). Chief Scientist: Gerhard Bohrmann (gbohrmann@marum.de) CR: https://www.tib.eu/en/search/id/awi%3Adoi~10.2312%252Fcr_m70/ CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2006/20060222.htm Raw data: not yet