Seabed photographs taken along OFOS profiles during POLARSTERN cruise PS96 (ANT-XXXI/2 FROSN) ...
Within the context of the overall ecological working programme Dynamics of Antarctic Marine Shelf Ecosystems (DynAMo) of the PS96 (ANT-XXXI/2) cruise of RV "Polarstern" to the Weddell Sea (Dec 2015 to Feb 2016), seabed imaging surveys were carried out along drift profiles by means of the O...
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| Format: | Article in Journal/Newspaper |
| Language: | English |
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PANGAEA
2016
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| Online Access: | https://dx.doi.org/10.1594/pangaea.862097 https://doi.pangaea.de/10.1594/PANGAEA.862097 |
| Summary: | Within the context of the overall ecological working programme Dynamics of Antarctic Marine Shelf Ecosystems (DynAMo) of the PS96 (ANT-XXXI/2) cruise of RV "Polarstern" to the Weddell Sea (Dec 2015 to Feb 2016), seabed imaging surveys were carried out along drift profiles by means of the Ocean Floor Observation System (OFOS) of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) Bremerhaven. The setup and mode of deployment of the OFOS was similar to that described by Bergmann and Klages (2012, doi:10.1016/j.marpolbul.2012.09.018). OFOS is a surface-powered gear equipped with two downward-looking cameras installed side-by-side: one high-resolution, wide-angle still camera (CANON® EOS 5D Mark III; lens: Canon EF 24 f/1.4L II, f stop: 13, exposure time: 1/125 sec; in-air view angles: 74° (horizontal), 53° (vertical), 84° (diagonal); image size: 5760 x 3840 px = 21 MPix; front of pressure resistant camera housing consisting of plexiglass dome port) and one high-definition color ... : According to the manufacturers' specifications, the GPS receiver of Polarstern (Trimble SPS461) has an accuracy of ?better than 5 m 3DRMS? (without differential signal that was not available during the cruise), and the GAPS system has an accuracy of 0.17% of slant ranges, which correlate best with cable lengths, which in turn were very close to water depths at the operational conditions of OFOS deployment during the cruise (e.g., small towing speed, so that OFOS was constantly hanging almost directly below the stern of the ship during the entire cast). However, the actual accuracy is known to be always less than the manufacturer's specifications because shipboard hydroacoustic systems are highly influenced by a variety of factors (e.g., transducer installation and calibration, ship's movements and noise, acoustic water-column characteristics). Therefore, the actual accuracies of Polarstern's underwater positioning systems were found to be 1 to 1.5% of slant range for 95% of the data, based on the ship's data ... |
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