The Quantification Scanning Sonar (QSS) was developed in 2017 by Dr. Yann Marcon, Professor Gerhard Bohrmann, and a team of engineers at the MARUM Center for Marine Environmental Sciences and the Department of Geosciences, University of Bremen, Germany. It was funded by the German Federal Ministry of Education and Research (BMBF) within the scope of the “M³: Monitoring Marine Methane” projects (grants 03F0765A and 03F0854A). The QSS focuses on selected vent sites at the summit of Southern Hydrate Ridge. It monitors the short-term variability of methane bubble plumes and changes in the seafloor morphology related to venting activity.
The QSS is a single-beam scanning sonar with an internal compass and a 360° scanning sector. The sonar is mounted on a 2.8 m high tripod (Figure 1). The QSS can operate at frequencies ranging from 500 kHz to 1.2 MHz. The beam width, which decreases with increasing operating frequencies, ranges from 45°x1.0° to 28°x0.6° (wide fan) and from 26°x1.2° to 20°x0.7° (narrow fan).
For most of its operating time, the QSS was set to operate at a frequency of 1000 kHz, a range of 20 m, a rotation angle of 360° and the minimum step size available (0.225°/step). The schedule consisted of one 15-minute long scanning sequence per hour. With these settings, a 15-minute scanning sequence recorded at least three consecutive 360° scans of the water column. However, the operation schedule of the QSS has changed a few times since the deployment of the instrument depending on the needs. The exact schedule can be inferred from the timestamp of the data files, while the operating settings can be retrieved from the data files.Access QNTSRA101 Data
Instrument Models & Deployed LocationsThe QSS was installed on the summit of Southern Hydrate Ridge, west of the "Einstein's Grotto" vent area at a water depth of 780 m (Figure 1). The instrument is connected to the medium-power junction box MJ01B. It consists of a single-beam scanning sonar (Kongsberg 1171 Series, High Resolution, Multi-frequency, Wide-Narrow Fan) with internal compass and a titanium tripod. The instrument control and data collection scheduling is done with the proprietary Kongsberg MS1000 software from the Regional Cabled Array shore side Operation Center, University of Washington.
Data FormatThe data products of each scanning sequence consist of:
- Raw data: one single file containing the data and metadata of the scanning sequence. The file name contains the starting time of the scanning sequence. The data are stored in the SMB format, a Kongsberg binary format described in the manufacturer's documentation (Kongsberg SMB File Format_900-00007904-2.1.pdf). SMB files can be readily played back with the Kongsberg MS1000 Express software, which can be freely redistributed for playback of the data (zip).
- Scan images: one image (.png format) for each 360° scan of the scanning sequence (Figure 2). The file name contains the starting time of the scanning sequence, and the number of the scan within the scanning sequence.
- Text files: one space-delimited text file for each 360° scan of the scanning sequence containing the scan data in readable format and expressed in polar coordinates centered on the sonar location. Each text file contains three two-dimensional arrays of integers representing respectively the direction (theta angle of polar coordinates, in thousandth degrees), the distance (radius of polar coordinates, in meters), and the sonar data value (strength of the returned signal) of every sample point of the scan. The file name contains the starting time of the scanning sequence, and the number of the scan within the scanning sequence.