This record describes multibeam echosounder data collected on RV Investigator voyage IN2023_V07, [FOCUS] which departed Hobart on the 15/11/23 and returned to Hobart on the 20/12/23. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter around the Antarctic Circumpolar Current in the Southern Ocean, South of Hobart. The EM710 MKII provides a 0.5° by 1° transmit and receive angular resolution respectively. The echosounder's nominal frequency range is from 40 to 100 kHz. Data are stored in *.all raw format for bathymetry and backscatter and *.wcd format for watercolumn backscatter at CSIRO. There are 55 files totalling 14.2 GB of raw 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. GPS tide was computed using the EGM2008 model and applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry grids in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2018_V05, 'How does a standing meander southeast of Tasmania brake the Antarctic Circumpolar Current?' which departed Hobart on the 16th October 2018 and returned to Hobart on the 16th November 2018. The objectives of the voyage included: (1) Deployment of a fleet of EM-APEX profiling floats, (2) Deployment of a tall mooring at the crest of a meander in the Polar Front of the Antarctic Circumpolar Current, (3) Full-depth hydrographic survey of the physics and biogeochemistry of the targeted ACC meander, conducting transects across the front and (4) Triaxus transects across and along the front. The Kongsberg EM710 MKII multibeam echosounder was used to acquire seafloor bathymetry and backscatter information during the departing transit from Hobart to a depth of around 1,177 m (at a position of 43.95°S; 147.78°E). The EM710 MKII provides a 0.5° by 1° transmit and receive angular resolution respectively. The echosounder's nominal frequency range is from 40 to 100 kHz. Data are stored in *.all raw format for bathymetry and backscatter at CSIRO. There are 12 files totalling 3.42 GB of raw 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. Tide corrections were not applied to the processed data. Processed data has 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 further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes scientific split-beam echosounder data collected on the RV Investigator voyage IN2018_V05, 'How does a standing meander southeast of Tasmania brake the Antarctic Circumpolar Current?' which departed Hobart on the 16th October 2018 and returned to Hobart on the 16th November 2018. The objectives of the voyage included: (1) Deployment of a fleet of EM-APEX profiling floats, (2) Deployment of a tall mooring at the crest of a meander in the Polar Front of the Antarctic Circumpolar Current, (3) Full-depth hydrographic survey of the physics and biogeochemistry of the targeted ACC meander, conducting transects across the front and (4) Triaxus transects across and along the front. The Simrad EK60 split beam echosounders 18, 38, 70 120, 200 and 333 kHz were used to acquire acoustic backscatter data to a range of 1500 m, from Hobart to Hobart. All frequencies were logged continuously (with the exception of occasional cessations required for acoustically quiet periods) for the extent of the voyage. The frequencies were set to passive during sensitive VMP deployment periods of the voyage in the ACC, when acoustic silent periods were requested by the science party. Data are stored in *.raw, *.bot and *.idx format at CSIRO. There are 1221 files totalling 105 GB of raw data in this dataset. No processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes sub bottom profiler data collected on RV Investigator voyage IN2018_V05, 'How does a standing meander southeast of Tasmania brake the Antarctic Circumpolar Current?' which departed Hobart on the 16th October 2018 and returned to Hobart on the 16th November 2018. The objectives of the voyage included: (1) Deployment of a fleet of EM-APEX profiling floats, (2) Deployment of a tall mooring at the crest of a meander in the Polar Front of the Antarctic Circumpolar Current, (3) Full-depth hydrographic survey of the physics and biogeochemistry of the targeted ACC meander, conducting transects across the front and (4) Triaxus transects across and along the front. The Kongsberg SBP120 (sub bottom profiler) was used to acquire data containing the specular reflections at different sediment interfaces below the seafloor. The SBP120 provides a 3° by 3° angular resolution. The echosounder's frequency sweep range is from 2.5 to 7 kHz. The SBP120 was logged for the extent of the voyage between Hobart and Hobart, but was set to passive mode during sensitive VMP deployment periods of the voyage in the ACC, when acoustic silent periods were requested by the science party. Data are stored in *.raw (297 files 5.67 GB) raw and *.seg (292 files 5.65 GB) segy formats at CSIRO. The segy format data had a real time processing stream applied, which applies gain, a gain correction, matched filter with replica shaping, an attribute calculation for instantaneous amplitude and time variable gain. Additional information regarding this dataset is contained in the GSM data acquisition and processing report. Additional data products may be available on request

This record describes gravity data collected on RV Investigator voyage IN2018_V05, 'How does a standing meander southeast of Tasmania brake the Antarctic Circumpolar Current?' which departed Hobart on the 16th October 2018 and returned to Hobart on the 16th November 2018. The objectives of the voyage included: (1) Deployment of a fleet of EM-APEX profiling floats, (2) Deployment of a tall mooring at the crest of a meander in the Polar Front of the Antarctic Circumpolar Current, (3) Full-depth hydrographic survey of the physics and biogeochemistry of the targeted ACC meander, conducting transects across the front and (4) Triaxus transects across and along the front. The gravity meter instrument is a MicroG Lacoste Air-Sea II. Data are stored in .ENV and .DAT data files at CSIRO. There are 64 files totalling 514 MB of raw data in this dataset. Wharf ties were not undertaken. Gravity data was acquired for the full duration of the voyage from Hobart to Hobart. No processing has been conducted on this data. Additional information regarding this dataset is contained in the GSM data acquisition and processing report.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2018_V05, 'How does a standing meander southeast of Tasmania brake the Antarctic Circumpolar Current?' which departed Hobart on the 16th October 2018 and returned to Hobart on the 16th November 2018. The objectives of the voyage included: (1) Deployment of a fleet of EM-APEX profiling floats, (2) Deployment of a tall mooring at the crest of a meander in the Polar Front of the Antarctic Circumpolar Current, (3) Full-depth hydrographic survey of the physics and biogeochemistry of the targeted ACC meander, conducting transects across the front and (4) Triaxus transects across and along the front. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter from Hobart to Hobart with particular emphasis on the scientific study area bounded between the following approximate coordinates: 54.156° to 57.344° (South) and 148.577° to 156.344° (East). The sonar was set to passive mode during sensitive VMP deployment periods of the voyage in the ACC, when acoustic silent periods were requested by the science party. 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 597 files totalling 18.6 GB of raw data in the dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.all format are corrected for motion and position. 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.

This record describes multibeam echosounder data collected on RV Investigator voyage IN2023_V07, [FOCUS] which departed Hobart on the 15/11/23 and returned to Hobart on the 20/12/23. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and watercolumn backscatter around the Antarctic Circumpolar Current in the Southern Ocean, South of Hobart. 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 1834 files totalling 105 GB of raw 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. GPS tide was computed using the EGM2008 model and applied to the processed data. Processed data has had outliers removed. Processed line data are available in *.gsf and ascii format, and processed bathymetry grids in geotiff format. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report. Additional data products may be available on request.

This record describes the Underway (UWY) data collected from the Marine National Facility (MNF) RV Investigator Voyage IN2020_V09 titled: "SOTS: Southern Ocean Time Series automated moorings for climate and carbon cycle studies southwest of Tasmania". The voyage took place between 27 August and 12 September, 2020 departing from Hobart (TAS) and arriving in Hobart (TAS). Standard Underway data is continuously recorded, consisting of: (1) Navigation data (NAV): Latitude, Longitude, Speed, Heading, Course Over Ground, Gyros, and Doppler Log (dual GPS instrument). (2) Thermosalinograph (TSG): Water Salinity, Flow-Rate, Temperature, Fluorescence, pCO2 and Optode/Oxygen. (3) Atmospheric (MET): Humidity, Wind Speed and Direction (vane and ultrasonic), Radiometer/Sea Surface Temperature, Pyranometer/Solar Radiation, Photosynthetically Active Radiation (PAR), Air Temperature, Air Pressure, Rain, Ozone and Trace Gases (port and starboard instruments). The quality-controlled RV Investigator underway meteorological and SST data are supplied to the IMOS AODN where they are publicly available at the "Ships of Opportunity" Thredds server (http://thredds.aodn.org.au/thredds/catalog/IMOS/SOOP/SOOP-ASF/VLMJ_Investigator/catalog.html) for research. From there, they are downloaded by NOAA for their In Situ Quality Monitoring web site (iQUAM2) and made available for satellite SST validation. The SBE 38 SST data are used within the Australian Bureau of Meteorology for real-time satellite SST validation and ingested into real-time SST analyses which are then used as the boundary condition for Numerical Weather Prediction models. The meteorological and SST data are uploaded onto the Global Telecommunications System (GTS) for global dissemination to Meteorological Agencies, and separately supplied to the SAMOS (http://samos.coaps.fsu.edu/html/) Project for air-sea flux research. The real-time SBE 38 SST data are currently (2017) used in the following data products (accessed via the GTS): • International Comprehensive Ocean-Atmosphere Data Set (ICOADS R3.0) (http://icoads.noaa.gov/) • NOAA NCEI Extended Reconstructed Sea Surface Temperature version 4 (ERSST.v4) (https://www.ncdc.noaa.gov/data-access/marineocean-data/extended-reconstructed-sea-surface-temperature-ersst-v4) • Hadley Centre SST Data Set (HadSST3) (http://www.metoffice.gov.uk/hadobs/hadsst3/) • Global Ocean Surface Underway Data (GOSUD) Project (http://www.gosud.org/) • Bureau of Meteorology daily and weekly SST analyses (http://www.bom.gov.au/marine/sst.shtml) • NOAA NCEI “Reynolds” daily global OISST analysis (https://www.ncdc.noaa.gov/oisst) • NASA JPL “MUR” 1 km daily global SST analysis (https://mur.jpl.nasa.gov/) • UK Met Office “OSTIA” daily global SST analysis (http://ghrsst-pp.metoffice.com/pages/latest_analysis/ostia.html) • CMC daily global SST analysis • Ourocean “G1SST” global daily 1 km SST analysis (https://ourocean.jpl.nasa.gov/SST) As part of the underway data gathering system, other datasets are produced (e.g., pCO2, ISAR SST) which are processed separately and have their own metadata records. Data are recorded at 5 second intervals. Near real-time data are available via the link "Visualisation tool for Underway Data." This dataset will be processed and archived within the CSIRO Oceans & Atmosphere (O&A) Information and Data Centre (IDC) in Hobart (TAS). Data are available at time intervals of 5 sec (NetCDF format), 10 sec and 5 min (ASCII format). Additional information regarding this dataset is contained in the Voyage Summary and/or the Data Processing Report for this voyage.

This record describes the Underway (UWY) data collected from the Marine National Facility (MNF) RV Investigator Voyage IN2020_V01, titled: “Development of William’s Ridge, Kerguelen Plateau: tectonics, hotspot magmatism, microcontinents, and Australia’s Extended Continental Shelf”. The voyage is scheduled to take place between January 10 and March 06, 2020 departing from Fremantle (WA) and returning back to Fremantle (WA). Standard Underway data is continuously recorded, consisting of: (1) Navigation data (NAV): Latitude, Longitude, Speed, Heading, Course Over Ground, Gyros, and Doppler Log (dual GPS instrument). (2) Thermosalinograph (TSG): Water Salinity, Flow-Rate, Temperature, Fluorescence, pCO2 and Optode/Oxygen. (3) Atmospheric (MET): Humidity, Wind Speed and Direction (vane and ultrasonic), Radiometer/Sea Surface Temperature, Pyranometer/Solar Radiation, Photosynthetically Active Radiation (PAR), Air Temperature, Air Pressure, Rain, Ozone and Trace Gases (port and starboard instruments). The quality-controlled RV Investigator underway meteorological and SST data are supplied to the IMOS AODN where they are publicly available at the "Ships of Opportunity" Thredds server (http://thredds.aodn.org.au/thredds/catalog/IMOS/SOOP/SOOP-ASF/VLMJ_Investigator/catalog.html) for research. From there, they are downloaded by NOAA for their In Situ Quality Monitoring web site (iQUAM2) and made available for satellite SST validation. The SBE 38 SST data are used within the Australian Bureau of Meteorology for real-time satellite SST validation and ingested into real-time SST analyses which are then used as the boundary condition for Numerical Weather Prediction models. The meteorological and SST data are uploaded onto the Global Telecommunications System (GTS) for global dissemination to Meteorological Agencies, and separately supplied to the SAMOS (http://samos.coaps.fsu.edu/html/) Project for air-sea flux research. The real-time SBE 38 SST data are currently (2017) used in the following data products (accessed via the GTS): • International Comprehensive Ocean-Atmosphere Data Set (ICOADS R3.0) (http://icoads.noaa.gov/) • NOAA NCEI Extended Reconstructed Sea Surface Temperature version 4 (ERSST.v4) (https://www.ncdc.noaa.gov/data-access/marineocean-data/extended-reconstructed-sea-surface-temperature-ersst-v4) • Hadley Centre SST Data Set (HadSST3) (http://www.metoffice.gov.uk/hadobs/hadsst3/) • Global Ocean Surface Underway Data (GOSUD) Project (http://www.gosud.org/) • Bureau of Meteorology daily and weekly SST analyses (http://www.bom.gov.au/marine/sst.shtml) • NOAA NCEI “Reynolds” daily global OISST analysis (https://www.ncdc.noaa.gov/oisst) • NASA JPL “MUR” 1 km daily global SST analysis (https://mur.jpl.nasa.gov/) • UK Met Office “OSTIA” daily global SST analysis (http://ghrsst-pp.metoffice.com/pages/latest_analysis/ostia.html) • CMC daily global SST analysis • Ourocean “G1SST” global daily 1 km SST analysis (https://ourocean.jpl.nasa.gov/SST) As part of the underway data gathering system, other datasets are produced (e.g., pCO2, ISAR SST) which are processed separately and have their own metadata records. Data are recorded at 5 second intervals. Near real-time data are available via the link "Visualisation tool for Underway Data." This dataset will be processed and archived within the CSIRO Oceans & Atmosphere (O&A) Information and Data Centre (IDC) in Hobart (TAS). Data are available at time intervals of 5 sec (NetCDF format), 10 sec and 5 min (ASCII format). Additional information regarding this dataset is contained in the Voyage Summary and/or the Data Processing Report for this voyage.