DOI: 10.1594/pangaea.860479
title: Gridded bathymetry from multibeam echosounder EM122 data of the cruise MSM33 (2013)

description: Bathymetry based on data recorded during MSM33 between 02.11.2013 –and 10.11.2013 in the Black Sea. The overarching goal of MSM33 was the investigation of the biology and biogeochemistry of the central Black Sea with a special consideration of the processes at pelagic redoxicline. The bathymetric focus laid upon the slope structure especially at the Archangelsky Ridge.
description: Detailed description:During the cruise MSM33 the Kongsberg EM122 multi-beam echo sounder was used. The EM122 uses a nominal sounding frequency of 12 kHz. 288 beams or 432 soundings, 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://www.km.kongsberg.com/. Multibeam profiling during MSM33 concentrated mainly the profiling of the slope structure in different areas throughout the Black Sea. Responsible person during this cruise / PI: Helge Wolfgang 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) that is retrievable through MB-System. In general, there is a tide differences of less than 20 cm in the Black Sea. Further roll, pitch and heave corrections were not necessary for the MSM33 data. Due to the fact that only one CTD cast near Sevastapol was taken into consideration for the acquisition throughout the study area some sound velocity problems in the data set had to be corrected. This correction of the 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). Changes in SVP were applied with the mbset function within mbsystem. 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.