Samples were obtained from the RV Investigator from 14 May - June 5, 2019 as part of the 2nd Indian Ocean Expedition (IIOE-2). A total of 20 stations (90 nautical miles apart) from 39.5 deg south to 11.5 deg S along the 110 ?E meridian was sampled during both day and night. The samples were obtained by means of hauls using a EZ multi-net with a 1 m2 mouth area and eight operating nets (500 µm mesh). It was sent down to 500 m depth and oblique hauls discriminating the following depth strata of the water column were taken as the net was retrieved: 500-400, 400-300, 300-200, 200-150, 150-100, 100-50, 50 - 5 m. Each stratum was sampled for about 10 min and the volume of water filtered was obtained via use of an electronically recording flowmeter (mean volume: 486.5 m3). In summary, 273 discrete stratum hauls, covering the upper 500 m of the water column, were made along the 110 deg E transect in the Indian Ocean. After sorting and identification of fish specimens on board, samples were preserved in 10% buffered formalin with borax for later inspection in the laboratory.

The aim of this study, as part of a large number of related studies, was to examine the occurrence of cetaceans and seabirds along the 110◦E meridian from temperate to tropical waters (39.5–11.5◦S). Cetaceans and seabirds were actively scanned for across a four-week period spanning austral autumn to winter. Acoustic recordings of vocalising cetaceans weremade using directional and omnidirectional sonobuoys (n = 87 deployments). In total, seven cetacean sightings (six baleen whale, one toothed whale), 186 seabird sightings and 225 cetacean acoustic detections were recorded. A total of 22 seabird species were sighted, including, petrels, albatrosses, tropicbirds, terns, shearwaters, boobies, frigatebirds, gannets, gulls, skuas and prions.

This record describes the Acoustic Doppler Current Profiler (ADCP) data collected from the Marine National Facility RV Investigator voyage IN2019_V03, titled: "A coupled bio-physical, ecosystem-scale, examination of Australia’s International Indian Ocean Expedition line." The voyage took place between May 14 and June 14, 2019 departing from Fremantle (WA) and arriving in Fremantle. Data was collected during in2019_v03 for the duration of the voyage. Data was collected using UHDAS and post-processed using CODAS. Both the RDI Ocean Surveyor 150kHz ADCP and the RDI Ocean Surveyor 75kHz ADCP were run in narrowband. Internal triggering was used. The drop keel was at 2m below the waterline for the duration of the voyage. See the voyage computing and electronics report for more details regarding data acquisition. This dataset was processed and then archived within the CSIRO Oceans and Atmosphere (O&A) Information and Data Centre (IDC) in Hobart.

This record describes Hydrology (HYD) data collected from the Marine National Facility (MNF) RV Investigator voyage IN2019_V03, titled: "A coupled bio-physical, ecosystem-scale, examination of Australia’s International Indian Ocean Expedition line 110E." The voyage took place from Fremantle (WA) to Fremantle between May 14 and June 14, 2019. Hydrology samples were collected from Niskin bottles sampled at various depths during Conductivity-Temperature-Depth (CTD) deployments. Parameters analysed were salinity, dissolved oxygen, phosphate, silicate, nitrate plus nitrite and ammonium. This dataset has been archived at the CSIRO O&A 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 data (CTD, Dissolved Oxygen, Transmissometer, PAR, ECO Triplet, Nitrate, Fluorescence and LOPC) collected using the towed TRIAXUS platform on Investigator voyage IN2019_V03, titled: "A coupled bio-physical, ecosystem-scale, examination of Australia’s International Indian Ocean Expedition line." The voyage took place between May 14 and June 14, 2019 departing from Fremantle (WA) and arriving in Fremantle. Data for 3 Triaxus deployments were acquired using seabirds SeaSave acquisition software with Seabird SBE911+ CTD #23. Sea-Bird and O&A Calibration lab supplied calibration factors were used to compute the pressure, preliminary conductivity, oxygen and temperature values. The data was subjected to automated QC to remove spikes and out-of-range values. Dissolved oxygen sensors, Photosynthetically Active Radiation (PAR) 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 and seconday sensors to produce an along-track time-series dataset for each data scan file. These files were grouped into sections/legs containing the Triaxus deployment. Moreover, for each section, vertical casts were created with interpolated values from the along-track time-series binned dataset with a maximum interpolation distance of 1 cast. These generated the along-track and vertical cast section data products for each Triaxus deployment. Throughout the voyage there were some issues with the Triaxus deployments. As a result, the standard data products could not be made for every deployment. See the Processing Report for further details. The collected data were subsequently archived within the CSIRO Oceans and Atmosphere (O&A) 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 Conductivity-Temperature-Depth (CTD) data collected from the Marine National Facility RV Investigator voyage IN2019_V03, titled: "A coupled bio-physical, ecosystem-scale examination of Australia’s International Indian Ocean Expedition Line." The voyage took place between May 13 and June 14, 2019 departing from Fremantle (WA) and arrivfing in Fremantle. Data for 54 deployments were acquired using the Sea-Bird SBE911 CTD #23 and #24, fitted with 36 twelve litre bottles on the rosette sampler. CSIRO-supplied calibrations factors were used to compute the pressures, temperature and preliminary conductivity values. The data were subjected to automated QC to remove spikes and out-of-range values. Chelsea Fluorometer, PAR Sensor, Altimeter, Wetlabs Transmissometer, UVP were also installed on the auxiliary A/D channels of the CTD. Additionally a Teledyne LADCP was installed on the CTD. The collected data were subsequently processed and archived within the CSIRO Oceans and Atmosphere (O&A) 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 Underway (UWY) data collected from the Marine National Facility (MNF) RV Investigator Voyage IN2019_V03, titled: "A coupled bio-physical, ecosystem-scale, examination of Australia’s International Indian Ocean Expedition line". The voyage took place between May 14 and June 14, 2019 departing from Fremantle (WA) and arriving in 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.

This record describes the End of Voyage (EOV) archive from the Marine National Facility (MNF) RV Investigator research voyage IN2019_V03, titled "A coupled bio-physical, ecosystem-scale, examination of Australia’s International Indian Ocean Expedition line." The voyage took place between May 14 and June 14, 2019 departing from Fremantle (WA) and arriving in Fremantle. For further information please refer to the voyage documentation links below. Instruments used and data collected include: Regular measurements: Acoustic Doppler Current Profiler (ADCP; 75, 150 KHz ), Lowered ADCP (LADCP), Cloud Condensation Nuclei counter (CCN), Condensation Particle Counters (CPC), Greenhouse Gas Analysers (Picarro), Radon and Ozone and sensors, Scanning Mobility Particle Sizers (SMPS), CTD, Hydrochemistry, Gravimeter, pCO2, Fisheries echosounder (EK60), Multibeam Echosounder (EM710, EM122), Sub-bottom Profiler (SBP120), GPS Positioning System, Doppler Velocity Log, Fluorometer, Oxygen optode, Thermosalinographs (TSG), Infrared Sea Surface Temperature Autonomous Radiometer (ISAR), Multiangle Absorption Photometer (MAAP), Nephelometer, Temperature, Humidity, Pressure, Wind and Rain sensors, Photosynthetically Active Radiation (PAR) sensor, Precision Infrared Radiometer (PIR), Precision Spectral Pyranometer (PSP), Weather Radar, Expendable Bathythermographs (XBTs). Voyage-specific measurements: DALEC radiometer, CE600 Underwater radiance camera, HyperPRO in-water profiling radiometer, Free-fall radiometer (C-OPS), Cytometry, Equilibrator Inlet Mass Spectrometry (EIMS), Vertical Microstructure Profiler (VMP), Triaxus, Submersible Ultraviolet Nitrate Analyser (SUNA), EZnet with video, Heron net, Indian Ocean Standard Net, Microzooplankton net, Neuston net, Continuous Plankton Recorder (CPR), Hydrophones, Microbes, Wildlife observations (seabirds, cetaceans and seals). The archive for the IN2019_V03 EOV raw data is curated by the CSIRO Oceans and Atmosphere (O&A) Information and Data Centre (IDC) in Hobart, with a permanent archive at the CSIRO Data Access Portal (DAP, https://data.csiro.au/dap/), providing access to participants and processors of the data collected in the voyage. All voyage documentation is available electronically to MNF support via the local network. Access to voyage documentation for non-CSIRO participants can be made via DataLibrariansOAMNF@csiro.au.