| Summary: | Quality of the multibeam bathymetric data was variable with some pervasive issues relating to vehicle motion (pitch/roll artefacts) and positioning during acquisition. Position error of the ROV exceeded the possible bathymetric grid size. The Isis ROV used ultra-short baseline (USBL) to obtain frequent absolute positions (each with rms error of 5 m) to correct for positional inaccuracies. Some raw data files did not import into the Caraibes software thus not all bathymetry data could be processed and included in the final grids. Gridded multibeam bathymetry data have horizontal square grid cell sizes of 0.25 - 0.5 m.,Multibeam bathymetric data was acquired by the Isis ROV on two dives during RRS James Clark Ross cruise JR157 in 2007. Dives 10 and 11 occurred on 29.01.07-31.01.07. Bathymetric data were processed for erroneous soundings and to correct vehicle motion in the Ifremer Caraibes software package, and then gridded in the open-source softwares GMT and MB-System. Processed, gridded data is available in NetCDF format.,The data has been collected using the Kongsberg Simrad MS-2000 echo-sounder mounted on Isis ROV,On cruise JR157 the Isis ROV was deployed on 15 dives in the Marguerite Trough area in January and February 2007. Dives 10 and 11 targeted a bedrock channel system on the inner continental shelf to investigate channel incision processes and the history of glaciation in the area. The plan was to map parts of the channel walls and thalweg, and then to use these data to locate the best coring sites within the channel system. In reality, several small patches of bathymetric data were acquired from the channels by a multibeam echosounder mounted on the ROV. This research was funded by UK Natural Environment Research Council grant AFI06/14 (NE/C506372/1) to J.A. Dowdeswell, R.D. Larter and G. Griffiths.
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