This record describes multibeam echosounder data collected on RV Investigator voyage IN2021_V03, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27 degrees South (multi-year)." The voyage took place from Hobart (TAS) to Brisbane (QLD) between May 8 and June 3, 2021. The Kongsberg EM710 MKII multibeam echosounder was used to acquire seafloor bathymetry and backscatter information and watercolumn backscatter between Hobart and Brisbane. 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 317 files totalling 41.9 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. The data has been reduced to approximate Mean Sea Level (MSL) using the Earth Gravitation Model 2008 (EGM2008) 1 arc-minute x 1 arc-minute grid spacing. GPS 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 gravity data collected on RV Investigator voyage IN2021_V03, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27 degrees South (multi-year)." The voyage took place from Hobart (TAS) to Brisbane (QLD) between May 8 and June 3, 2021. The gravity meter instrument is a MicroG Lacoste Air-Sea II. Data are stored in .ENV and .DAT data files at CSIRO. There are 62 files totalling 462 MB 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.

This record describes sub bottom profiler data collected on RV Investigator voyage IN2021_V03, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27 degrees South (multi-year)." The voyage took place from Hobart (TAS) to Brisbane (QLD) between May 8 and June 3, 2021. 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 continuously for the extent of the voyage. Data are stored in *.raw (9,960 files 20.9 GB) raw and *.seg (9,956 files 20.8 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 XBT data collected on RV Investigator voyage IN2021_V03, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27 degrees South (multi-year)." The voyage took place from Hobart (TAS) to Brisbane (QLD) between May 8 and June 3, 2021. A total of 31 XBT casts were conducted over the duration of this voyage. 25 XBT casts were considered good and used for processing. Data are stored in netCDF files at CSIRO. 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 multibeam echosounder data collected on RV Investigator voyage IN2021_v03, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27 degrees South (multi-year)." The voyage took place from Hobart (TAS) to Brisbane (QLD) between May 8 and June 3, 2021. The Kongsberg EM122 multibeam echosounder was used to acquire seafloor bathymetry, backscatter information and water column backscatter, during the transit and at the East Australian Current (EAC) Moorings site. 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 (459 files 26.4 GB) and backscatter and *.wcd format for watercolumn backscatter (423 files 28.9 GB) at CSIRO. 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 has been reduced to approximate Mean Sea Level (MSL) using the Earth Gravitation Model 2008 (EGM2008) 1 arc-minute x 1 arc-minute grid spacing. Tide corrections were not applied to the processed data. Processed data had outliers removed. Processed line data are available in *.gsf (version 3.0.9) and ascii format, and processed bathymetry 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 Hydrology (HYD) data collected from the Marine National Facility (MNF) RV Investigator voyage IN2021_V03, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27S." The voyage took place between May 8 and June 3, 2021 departing from Hobart (TAS) and arriving in Brisbane (QLD). Nutrient samples were analysed using segmented flow SEAL AA3 and results are in µmol/L. In-house methods SOP 001, SOP 002, SOP 003 and SOP 004 were used to analyse nutrients. Please cite the following paper when using Hydrochemistry data for silicate, phosphate, nitrate+nitrite (NOx) and nitrite analysis: Rees, C., L. Pender, K. Sherrin, C. Schwanger, P. Hughes, S. Tibben, A. Marouchos, and M. Rayner. 2018. Methods for reproducible shipboard SFA nutrient measurement using RMNS and automated data processing. Limnol. Oceanogr: Methods Doi:10.1002/Iom3.10294 Salinities were analysed using Guildline 8400B Autosal Lab Salinometer and OSIL software. The salinometer was calibrated with IAPSO standard seawater P163 and P164. In-house method SOP 006 was used to analyse salinity, units are Practical Salinity Unit (PSU). Dissolved Oxygens were analysed using Scripps UV titrator and software, units measured in ml/L and converted to µmol/L. Dissolved oxygen was analysed using in-house method SOP 005. All data was processed with HyPro 5.7 on the ship and any data re-processed on shore was with HyPro 5.7. A copy of HyPro is available with the data. Nutrient data decimal places within the CSV file; silicate is 1 decimal place, nitrite is 3 decimal places and NOx (nitrate + nitrite), phosphate and ammonium is 2 decimal places. Previously values below detection limit were set to zero these values are now displayed as the measured value even if that is a negative value. Oxygen Data is displayed to 3 decimal places. Salinity data is displayed to 4 decimal places, prior to in2018_t01 voyage it was 3 decimal places in the csv file. Data processing notes are in the process report (in2021_v03_HYD_ProcessingReport.pdf). This dataset has been archived at the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC) in Hobart. Additional information regarding this dataset is contained in the Voyage Report and Data Processing Report.

This record describes the Conductivity-Temperature-Depth (CTD) data collected from the Marine National Facility RV Investigator voyage IN2021_V03, titled: "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27o S." The voyage took place between May 8 and June 3, 2021 departing from Hobart (TAS) and arriving in Brisbane (QLD). Data for 36 deployments were acquired using the Sea-Bird SBE911 CTD 24, fitted with 19 twelve litre bottles on the rosette sampler. Sea-Bird-supplied calibration factors were used to compute the pressures and preliminary conductivity values. CSIRO -supplied calibrations were applied to the temperature data. The data were subjected to automated QC to remove spikes and out-of-range values. The final conductivity calibration was based on a single deployment grouping. The final calibration from the primary sensor had a standard deviation (SD) of 0.0019084 PSU, when rounded this is outside our target of ‘better than 0.002 PSU’, so the cut-off was adjusted to 0.003 PSU. The standard product of 1 decibar binned averaged were produced using data from the primary sensors. Cast 10 was ended prematurely so CapPro could not process cast properly. To overcome this, in MATLAB, the end of cast 9 was attached to the end of cast 10. This data will not appear in the raw files from SeaSave and should not affect processing, as CapPro will remove out of water data before processing but needs this data to find the end of the cast. During cast 12 the CTD landed on the bottom of the ocean floor, no damage was found, and all subsequent casts performed as expected. Prior to cast 31, due to some discrepancies between the primary and secondary sensors, the Seagoing Instrumentation Team swapped the secondary pump. This resolved the particular issue. Bottle seven had intermittent problems firing reliably. Initially the release magnet was swapped and all further casts had a backup fired with bottle 7, however it was later found that the root cause was corrosion under the epoxy. As a precaution, the whole trigger mechanism was swapped. The dissolved oxygen data calibration fit had a SD of 0.84461μM. The agreement between the CTD and bottle data was good. PAR, Transmissometer, CDOM, Altimeter and Ecotriplet were also installed on the auxiliary A/D channels of the CTD. The collected data were subsequently processed and archived within the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC) in Hobart. Additional information regarding this dataset may be contained in the Voyage Summary and the CTD Data Processing Report.

This record describes the data (CTD, Dissolved Oxygen, Transmissometer, PAR, ECO Triplet, Nitrate, Fluorescence and LOPC) collected using the towed TRIAXUS platform on Investigator voyage IN2021_V03, titled: "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27 degrees South (multi-year)." The voyage took place from Hobart (TAS) to Brisbane (QLD) between May 8 and June 3, 2021. Data for 8 Triaxus tows were acquired using Seabird’s Seasave acquisition software using the Seabird SBE911+ CTD #25. Sea-Bird and O&A Calibration lab supplied calibration factors were used to compute the pressure, preliminary conductivity, oxygen and temperature values. The data were subjected to automated QC to remove spikes and out-of-range values. SUNA sensors were also installed on the auxiliary A/D channels of the CTD. In addition to the auxiliary channels, an ECO Triplet and LOPC were mounted on the Triaxus as attached payloads. The standard data product (1 decibar/10 second binned averaged) was produced using data from the primary sensors to produce an along-track time-series dataset for each data recording file. These files were grouped into sections containing each Triaxus tow and in each tow, vertical casts were created with interpolated values from the along-track time-series binned dataset with a maximum interpolation distance of 8 cast. These generated the along-track and vertical cast section data products for each Triaxus tow. Throughout the voyage there were numerous issues with the Triaxus vehicle. As a result, standard data products could not be made for a number of deployments. The collected data were subsequently archived within the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC) in Hobart. Additional information regarding this dataset may be contained in the Voyage Summary and the Data Processing Report.

This record describes the Underway (UWY) data collected from the Marine National Facility (MNF) RV Investigator Voyage IN2021_V03, titled "Integrated Marine Observing System: monitoring of East Australian Current property transports at 27o S." The voyage took place between May 8 and June 3, 2021 departing from Hobart (TAS) and arriving in Brisbane (QLD). 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 National Collections and Marine Infrastructure (NCMI) 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.