Wintersteller, Paul; Titschack, Jürgen; Gaide, Stefanie; Hanebuth, Till J J; Freiwald, André; Westphal, Hildegard (2017): Gridded EM120 multibeam-echosounder bathymetry of cruise MSM16-3 [dataset]. MARUM - Center for Marine Environmental Sciences, University Bremen, PANGAEA, https://doi.org/10.1594/PANGAEA.883749

Bathymetry based on data recorded during MSM16-3 between 13.10.2010 and 20.11.2010 at the Mauritanian shelf. The expedition aimed at a comprehensive understanding of the complex sedimentary system off Mauritania as an atypical tropical ecosystem and an archive of paleoclimatic change in Africa during the Holocene. Responsible person during this cruise / PI: Andre Freiwald, Till Hanebuth & Stephen Schilling.

Chief Scientist: Hildegard Westphal (director.zmt leibniz-zmt.de)

Description of processed data sources:

The hullmounted Kongsberg EM120 uses a nominal sounding frequency of 12 kHz. 191 beams with a 2°/2° footprint are formed for each ping while the seafloor is detected using amplitude and phase information for each beam sounding. For further information consult https://epic.awi.de/26725/1/Kon2007a.pdf. The EM120 was mainly used at water depths beyond 800 m while to critical problems were detected.

Description of data processing:

Postprocessing and products were conducted by the Seafloor-Imaging group of MARUM, responsible person & CI Citation: Jürgen Titschack (jtitschack@marum.de) & Paul Wintersteller (seafloor-imaging@marum.de). The MB-system suite (Caress, D.W., and D.N. Chayes, MB-System Version 5, Open source software distributed from the MBARI and L-DEO web sites, 2000-2017) 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. Further roll, pitch, heave were not applied for the MSM16-3 data. Bathymetric data has been manually cleaned for existing artefacts with mbeditviz. The data has been ray-traced using different sound velocity profiles (SVP) manually modified after CTDs taken in the area and/or global SVP/CTD databases. 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 70m. 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.