Gridded EM122 multibeam-echosounder bathymetry of METEOR cruise M112

Gridded bathymetry based on acquisition recorded during M112 between 06.11.2014 and 15.12.2014 in the eastern Mediterranean Sea. The aim of the cruise was to investigate in mud volcanoes of the Calabrian Arc in Italian waters, where 54 potential mud volcanoes have been documented while it remained unclear whether they are still active or not. Therefore, the bathymetric surveys were accompanied with investigations in the water column. Several sound velocity profiles (SVPs) were taken to correct the bathymetry. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry post-processing and its products. Description of the data source: During the cruise M112 the Kongsberg EM122 multibeam echosounder with a nominal sounding frequency of 12 kHz was utilized. 288 beams (and up to 864 soundings in equidistant and dual swath mode) are formed for each ping with a 1°(Tx)/2°(Rx) footprint while the seafloor is detected using amplitude and phase information for each beam sounding. For further information consult https://www.km.kongsberg.com/. The EM122 was recording constantly within the permitted areas, either designated to bathymetry surveys or flare imaging-surveys. Responsible person during this cruise / PI: Paul Wintersteller (pwintersteller@marum.de) and Christian Ferreira (cferreira@marum.de). Description of data processing: Postprocessing and products were conducted by the Seafloor-Imaging & Mapping group of MARUM, 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 5.5, Open source software distributed from the MBARI and L-DEO web sites, 2000-2012.) was utilized for this purpose. A tide correction was applied, based on the Oregon State University (OSU) tidal prediction software (OTPS) that is retrievable through MB-System. CTD measurements were taken during the M112 cruise and these were sufficient to represent the changes in the sound velocity (SVP) throughout the study area. Further roll, pitch and heave corrections were not applied for the M112 data. Bathymetric data has been manually cleaned for existing artefacts with mbeditviz. NetCDF (GMT) grids of the product and the statistics were created using mbgrid. No total propagated uncertainty (TPU) has been calculated to gather vertical or horizontal accuracy. The currently published bathymetric grid of the cruise has a resolution of 70 m. For scientific purposes a higher resolution is at least partly, achievable and is used. 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: G. Bohrmann gbohrmann@marum.de CSR: http://www.bsh.de/aktdat/dod/fahrtergebnis/2014/20140278.htm

A special thanks goes to the watch keeper of the hydroacoustic systems during M112: M. Wiebe, D. Praeg, C. Johansen,O. Candoni, T. Biller, W. Menapace

Another thanks goes to the student helpers, that helped to create the product: T. Biller, N. Brueckner