DOI: 10.1594/pangaea.912937
title: Gridded bathymetry from EM122 multibeam echosounder of R/V Maria S. Merian cruise MSM44

description: Bathymetry data was acquired during R/V MARIA S. MERIAN cruise MSM44 in the northeastern Baffin Bay between 30.06.2015 and 30.07.2015. The cruise carried out multidisciplinary research in order to investigate the deglaciation history of the Greenland Ice Sheet (GIS). To research the involved ocean, cryosphere and climate processes and feedbacks and to address the complex spatial and temporal distribution patterns of the marine GIS terminations in the northeast Baffin Bay, RV MARIA S. MERIAN visited sites in the Davis Strait, the Uumannaq Trough, and the Melville Bay during expedition MSM44. The objectives were to systematically search for and map glacigenic seafloor features providing information on the maximum extend and retreat histories of ice sheets since the last glacial maximum and during the Holocene. Extensive mapping was conducted due to the fact, that several huge parts of Greenland's coast are only insufficiently mapped or completely uncharted and thus are barely reliable in concern of navigation and interpretation towards glacigenic features of the last ice ages. CI Citation: Paul Wintersteller (seafloor-imaging@marum.de) as responsible party for bathymetry raw data ingest and approval.Description of processed data sources:During the MSM44 cruise, the hull-mounted KONGSBERG EM122 multibeam echosounder (MBES) was utilized to perform bathymetric mapping in medium to deep waters. Two linear transducer arrays in a Mills Cross configuration transmit acoustic signals of a nominal sonar frequency of 12 kHz. With 432 soundings per swath, the emission cone has a dimension of 150° across track and 2° along track. With a reception obtained from 288 beams, the actual beam footprint is 2° by 2°. Depending on the roughness of the seafloor and the water depth, the swath width on a flat bottom is maximum six times the water depth. For further information on the system, consult https://www.km.kongsberg.com/. The position and depth of the water column is estimated for each beam by using the detected two-way-travel time and the beam angle, ray-traced through the water column, utilizing a proper sound speed profile. Motion sensor data such as roll, pitch and heading as well as the time synchronization of the GPS clock and positioning via GPS were applied during data acquisition within the system, to ensure correct seafloor mapping. The multibeam surveys were generally run at 8 knots. During deep water surveys &gt;500 m generally a swath angle of about 130° was used. In shallow water, the swath angles were set to a maximum of 150°. During the entire cruise two complete system break downs happened where a manual restart was performed. Responsible person during this cruise / PI: Laura Jensen & Simon Dreutter (simon.dreutter@awi.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 (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, https://www.mbari.org/products/research-software/mb-system, 2017) was utilized for this purpose. Tide and a sound velocity profile were applied to the MSM44 data; there were no corrections for roll, pitch and heave. Using Mbeditviz, artefacts were cleaned manually. NetCDF (GMT) grids of the edited data as well as statistics were created with mbgrid. The published bathymetric EM122 grid of the cruise MSM44 has a resolution of 35 m. No total propagated uncertainty (TPU) has been calculated to gather vertical or horizontal accuracy. 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. The DTMs projections are given in Geographic coordinate system Lat/Lon; Geodetic Datum: WGS84. All grids produced are retrievable through the PANGAEA database (www.pangaea.de).Chief Scientist: Boris DorschelCR: https://www.tib.eu/de/suchen/id/awi%3Adoi~10.2312%252Fcr_msm44/CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2013/20130053.htm