DOI: 10.1594/pangaea.900987
title: Gridded bathymetry from multibeam echosounder EM122 data of METEOR cruise M114 (Southern Gulf of Mexico)

description: During the RV Meteor cruise M114, which took place between 12.02.2015 to 28.03.2015, bathymetry data based on the multibeam echosounder EM122 (MBES) was recorded. The research area is located in the southern Gulf of Mexico (Campeche Bay). The main focus of the cruise was the investigation of seafloor structures, which are related to asphalt deposits on top of submarine ridges and knolls, known as salt diapirs. During the second leg of M114 the ROV QUEST 4000m was utilized to collect samples of these asphalt deposits. The ship-mounded multibeam echosounder was used to collect detailed information about these structures, therefore bathymetry but also backscatter data was recorded continuously. Additionally water column data was used to locate gas bubble emission sites. 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 RV METEOR cruise M114 the KONGSBERG EM122 multibeam echosounder with a nominal sounding frequency of 12 kHz was utilized. 288 beams (and up to 400 soundings in equidistant and dual swath mode) are formed for each ping with a 1°(Tx)/2°(Rx) footprint while the seafloor is detected using amplitude and phase information for each beam sounding. For further information consult https://www.km.kongsberg.com/. The EM122 was recording constantly within the permitted areas, either designated to bathymetry surveys or flare imaging-surveys. It was running without any problems with regard to hardware or software during the whole cruise. The weather and sea state was mostly cooperative. Nevertheless, the data quality deteriorated due to higher winds and sea states at a few days during the cruise. Responsible person during this cruise / PI: Christian Ferreira (cferreira@marum.de) & Paul Wintersteller (pwintersteller@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 suite (Caress, D.W., and D.N. Chayes, MB-System Version 5.5, 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. Bathymetric data has been manually cleaned for existing artefacts with mbeditviz. 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 30 m. 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. Chief Scientists: Heiko Sahling and Gerhard Bohrmann CR: https://www.tib.eu/en/search/id/awi%3Adoi~10.2312%252Fcr_m114/ CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2015/20150003.htm A special thanks goes to the following watchkeeper of cruise M114: M. Römer, J.-D. Groeneveld, M. Breitzke, C.-W. Hsu, M. Loher, M. Wiebe, A. Gaytan, L. Jimenez, D. Smrzka, J. Zwicker. Final processing has been supported by Tiago Biller, Nils Brückner and Stephanie Gaide as student assistants.