Gridded bathymetry from multibeam echosounder ELAC SB3050 data of POSEIDON cruise PO462 (Eastern Mediterranean Sea, Anaximander Mountains)

Bathymetry data based on Multibeam echosounder SB3050 (MBES) was recorded during RV POSEIDON cruise POS462 between 28.10.2013 and 21.11.2013 in the Eastern Mediterranean Sea. The prime objective of the cruise was the investigation of the 'Anaximander Mountains' south of Turkey and therefore to decipher key processes of mud volcanoes, which led to the emission of gas hydrates in shallow marine sediments. During 8 AUV and several MBES surveys, four mud volcanoes were mapped. The detailed mapping of these mud volcanoes and identification of gas hydrate emissions were the main research interests of the hydroacoustic group on board. Additionally samples of the mud volcanoes were taken using a gravity corer and heat/flow measurements were done. 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 POSEIDON cruise POS460 the ship-mounted ELAC SB3050 multibeam echosounder with a nominal sounding frequency of 50 kHz was utilized. A maximum of 384 beams with a 1.5°(TX)/2°(RX) footprint are formed for each ping while the seafloor is detected using amplitude and phase information for each beam sounding. For further information consult http://www.mdsys.co.kr/down/ELAC/SB_3050.pdf. A maximum range of 2000 was achieved, which caused limitations of the mapped area. Due to static beam positions and angles of the ELAC system the number of beams was reduced according to the depth. In shallower parts a maximum of 160/180 beams were produced. In comparison, in deeper parts (1800/2000m), these numbers were reduced by 40 beams. The Hydrostar software by ELAC was used to gather data. Problems with the navigation sensor and motion sensor CODA F180 were reported (further information can be found in the cruise report). Responsible person for hydroacoustic during this cruise / PI: Christian dos Santos Ferreira (cferreira@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 5.4., Open source software distributed from the MBARI and L-DEO web sites, 2000-2012.) was utilized for this purpose. No tide correction was applied. Five CTD measurements were taken during the POS462 cruise, and these were sufficient to represent the changes in the sound velocity throughout the study area. Further pitch and heave corrections were not applied for the POS462 data though a roll off-set of 1.5° was applied (mbset). 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. All grids produced are retrievable through the PANGAEA database (www.pangaea.de). Chief Scientist: Gerhard Bohrmann (gbohrmann@marum.de) CR: http://elib.suub.uni-bremen.de/edocs/00103551-1.pdf CSR: https://www2.bsh.de/aktdat/dod/fahrtergebnis/2013/20130095.htm Bathymetric raw-dataset published: not yet A special thanks goes to the watchkeeper: Ammar Aljuhne, Miriam Röme