DOI: 10.1594/pangaea.860478
title: Gridded bathymetry from multibeam echosounder EM120 data of the cruise MSM15/2 (2011)

description: Bathymetry based on data recorded during MSM15-2 between 10.05.2010 and 02.06.2010 in the Black Sea. The aim of the cruise was to perform AUV and ROV pre-site surveys of potential drill sites that represent deposits where shallow gas hydrates have already been sampled by gravity and piston coring and where gas emissions to the water column have been detected.
description: Detailed description:During the MSM15-2 cruise the Kongsberg EM120 multi-beam echo sounder was used. The 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. During MSM15-2 three bathymetric datasets were surveyed with the EM120, though the main focus of MSM15-2 was the surveying of flare areas with the ROV QUEST and the AUV SEAL 2000 (both owned by marum). Responsible person during this cruise / PI: Paul Wintersteller (pwintersteller@marum.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. Though CTD measurements were taken during the MSM15-2 cruise, these were not sufficient to represent the changes in the sound velocity profile (SVP) throughout the study area, therefore a SVP correction had to be applied partly. 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). Due to a positive offset within the data set a negative draft correction of 5 m had to be applied with mbset while further roll, pitch and heave corrections were not necessary for the MSM15-2 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. 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.