dos Santos Ferreira, Christian; Wintersteller, Paul (2016): Gridded bathymetry from multibeam echosounder HS-DS2 data of the cruise M51/4 (2001) [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.860033

Bathymetry based on data recorded during M51-4 between 13.12.2001 and 28.12.2001 in the Black Sea. The purpose of the present-study was to sample sediments and the water columns of the nw/sw Black Sea and the E Marmara Sea to study a) a high resolution sediment records of Holocene climate, b) biogeochemical associated with deep anaerobic methane oxidation, and c) element cycling in the stratified water column. Bathymetric data (hydrosweep + parasound) was primarily used to choose appropriate sites for coring of undisturbed sediments. Samples were taken for future analyses of abundance and activity of bacteria, geochemistry and dating.

Detailed description:

During the cruise M51-4 the ATLAS Hydrosweep (HS-DS) multi-beam echo-sounder was used. The HS-DS uses a nominal sounding frequency of 15.5 kHz. 59 beams across a 90° angle are formed for each ping while the seafloor is detected using amplitude and phase information for each beam sounding.

HS-DS multibeam data were recorded on R/V METEOR, in parallel to sub-bottom profiling data in the working areas in the Marmara Sea, the NW Black Sea, and the SW Black Sea. PI: Helge Arz (helge.arz@io-warnemuende.de).

Description of data processing:

Postprocessing and products were conducted by the Seafloor-Imaging group of MARUM, responsible person: Paul Wintersteller (seafloor-imaging@marum.de). The open source software MB-system (Caress, D.W., and D.N. Chayes, MB-System Version 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) which is retrievable through MB-System. In general, there is a tide differences of less than 20 cm in the Black Sea. Due to the fact that no sound velocity profiles (SVP) were obtained during the cruise, they have been applied during post processing. The later correction of sound velocity is based on various SVP/CTD measurements throughout different cruises in the Black Sea within the last 15-20 years. In addition, the NATO Black Sea data base (http://sfp1.ims.metu.edu.tr/ODBMSDB/ODBMSDB.dll/querydb) was consulted for further CTD profiles in the given season/period of the year and in close position to the data set. The CTD data has then been used to calculate SVP by the usage of the UNESCO formula (G.S.K. Wong and S Zhu, Speed of sound in seawater as a function of salinity, temperature and pressure (1995) J. Acoust. Soc. Am. 97(3) pp 1732-1736). The changes in SVP were applied with the mbset function within mbsystem. Motion, lever-arm or offset corrections e.g. for roll, pitch or heading were not applied. Bathymetric data has been manually cleaned for existing artefacts with mbeditviz. NetCDF (GMT) grids of the product and the statistics were created using mbgrid. Quality assurance was furthermore proven by visual and statistical comparison of crossing survey-lines from different cruises throughout the Black Sea. 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 125 m. A higher resolution is, at least partly, achievable.