This record describes multibeam echosounder data collected on RV Investigator voyage IN2021_V04 (Biodiversity Assessment of Australia’s Indian Ocean Territories), which departed Darwin on the 30th June 2021 and returned to Hobart on the 29th July 2021.
The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter between Scott Reef (Northern Territory) and south west shelf of Tasmania.
The EM122 provides a 1 degree by 1 degree angular resolution. The echosounder's nominal frequency is 12 kHz.
Data are stored in .all raw format for bathymetry and backscatter and .wcd format for watercolumn backscatter at CSIRO. There are 715 files totalling 43.2 GB of raw bathymetry & backscatter data, and 715 files totalling 60.3 GB of raw watercolumn data in this dataset..
Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in .all format are corrected for motion and position.
The data have been reduced to approximate Mean Sea Level (MSL) using the Earth Gravitation Model 2008 (EGM2008) 1 arc-minute grid. Tide corrections were not applied to the processed data. Processed data had outliers removed. Processed line data are available in .gsf and ascii format, and processed bathymetry and backscatter grids in geotiff format.
Additional information regarding this dataset, including information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.