Gaide, Stefanie; Römer, Miriam (2021): Sediment echosounder raw data (Atlas Parasound P70 echosounder entire dataset) of RV MARIA S. MERIAN during cruise MSM98 [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.937631

Sediment echosounder data using Atlas Parasound P70 echosounder was recorded during MARIA S. MERIAN cruise MSM98, which took place in the North Sea from 2021-01-08 to 2021-01-23. The main objective of the cruise was focused on the hydrocarbon fluid emissions in the German North Sea and focused on the 'Entenschnabel'- area. During MSM98 the newly detected gas emissions were investigated in detail regarding its quantities, temporal and spatial variability, source and fate. Description of data source: During the MSM98 cruise, the hull-mounted parametric sub-bottom profiler ATLAS PARASOUND P70 was used to conduct information about the sediment sub-surface and water column. Its function is based on the parametric effect of the non-linear relation of pressure and density during sonar propagation. The system utilizes two high-intensity waves with frequencies of 18-20 kHz (primary high frequency; PHF) and 22-24 kHz to create a secondary high (about 40-42 kHz) and secondary low frequency (SLF) of about 4 kHz. The SLF can record sub-bottom structures, whereas the PHF can image the water column and potential gas bubbles, plankton ,fish or nepheloid layers within. The transducer array has an opening angle of 4° by 5°, which corresponds to a footprint size of about 7% of the water depth. Data acquisition was performed using measured real-time values of surface sound velocity and a static sound velocity profile of 1500 m/s. Using the software ATLAS PARASTORE, data was displayed and stored as raw *.asd files and additional *.ps3 and auxiliary files for certain depth windows. The *.ps3 files were utilized for conversion to SEG-Y format and further processing using the software SeNT (developed by V. Spiess & H. Keil, MTU-GeoB) and Kingdom Suite. For further information on the system, consult: https://epic.awi.de/id/eprint/26733/7/ATLAS_PARASOUND_2015-02.pdf. The sub-bottom profiler was operating almost continuously with a desired frequency of 4 kHz for SLF and a desired frequency of 18 kHz for PHF. Most of the time the system run as continuous wave for water column analyisis.