DOI: 10.1594/pangaea.912777
title: Gridded bathymetry from EM710 multibeam echosounder of R/V Meteor cruise M86/1A

description: Bathymetry data was acquired during R/V METEOR cruise M86/1a in the Baltic Sea between 04.11.2011 and 22.11.2011. The main aim was to examine whether salinity-related phylogenetic shifts in microbial communities imply relevant functional changes along the whole lateral Baltic salinity gradient between the Skagerrak and the Bothnian Bay. 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 M86/1a cruise, the hull-mounted KONGSBERG EM710 multibeam echosounder (MBES) was utilized to perform bathymetric mapping of high resolution in water depths of 3 m to – theoretically – 2000 m. Two linear transducer arrays in a Mills Cross configuration transmit acoustic signals of a nominal sonar frequency 70 to 100 kHz. The emission cone has a dimension of 150° across track and 1° along track. With a reception obtained from 256 beams, the actual beam footprint is 1° by 1°. Depending on the roughness of the seafloor, the swath width on a flat bottom is generally maximum 5.5 times the water depth. For further information on the system, consult https://www.km.kongsberg.com/. The position and depth of the water column is estimated for each beam by using the detected two-way-travel time and the beam angle known for each beam and taking ray bending due to refraction in the water column by sound speed into account. During the M86/1a cruise the EM710 was operated in the predefined (notified) survey areas only: Skagerrak, German EEZ (Mecklenburg Bay up to Arkona Basins) and in the Landsort Deep. Responsible person during this cruise / PI: Christian dos Ferreira (cferreira@marum.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. Tide and a sound velocity profile were applied to the M86/1a data; there were no corrections for roll, pitch and heave applied. Using Mbeditviz, artefacts were cleaned manually. NetCDF (GMT) grids of the edited data as well as statistics were created with mbgrid. The published bathymetric EM710 grid of the cruise M86/1a 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: Helge ArzCR: https://www.tib.eu/de/suchen/id/awi%3Adoi~10.2312%252Fcr_m86_1ab/CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2011/20110443.htm