This record describes the EM-APEX Floats data from the Marine National Facility (MNF) RV Investigator voyage IN2023_V07, titled "SWOT-ACC: smaller scales of the Antarctic Circumpolar Current in a meander south of Tasmania." The voyage took place between November 15, 2023 and December 20, 2023 (AEST), departing from Hobart and returning to Hobart. Two EM-APEX floats were deployed to measure high-resolution profiles of temperature, salinity, pressure, and horizontal velocity in the Antarctic Circumpolar Current. These observations provide critical subsurface data to link small-scale variability in sea surface height observed by the SWOT satellite with underlying ocean circulation, eddy activity, and cross-front transport of heat and carbon. Tracking of the EM-APEX floats is available via the interactive map link, using hull numbers f10331 and f10317.

This record describes Hydrology (HYD) data collected from the Marine National Facility (MNF) RV Investigator voyage IN2023_V07, titled: "SWOT-ACC : Smaller Scales Of The Antarctic Circumpolar Current In A Meander South Of Tasmania." The voyage took place between November 15 and December 20, 2023, departing from Hobart (TAS) and returning to Hobart. 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 processed (quality-controlled), and 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 CTD data collected on Investigator voyage IN2023_V07, titled: "SWOT-ACC: smaller scales of the Antarctic Circumpolar Current in a meander south of Tasmania." The voyage took place between November 15, 2023 and December 20, 2023 (AEST), departing from Hobart and returning to Hobart. The primary focus of this voyage was to enhance our ability to observe and comprehend the effects of small-scale motions (ranging from 10 to 100 km) on the dynamics of the Antarctic Circumpolar Current (ACC). The groundbreaking Surface Water Ocean Topography (SWOT) satellite mission will provide unprecedented measurements of sea surface height over a wide area with substantially improved spatial resolution compared to traditional altimeters. While SWOT will offer unparalleled coverage in both space and time, it is crucial to obtain in situ subsurface ocean measurements to validate the satellite observations and establish the connection between small-scale variability in sea surface height and subsurface ocean circulation and dynamics. Data for 111 CTD deployments were acquired using the Sea-Bird SBE9+V2 CTD unit #24 (S/N 1332), fitted with 36 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 0.0012454 PSU, within our target of ‘better than 0.002 PSU’. The standard product of 1-decibar binned averages were produced using data from the primary sensors. The dissolved oxygen data (primary) calibration fit had a SD of 0.78388 μM. The agreement between the CTD and bottle data was good. Additional sensors include: SUNA Nitrate, Altimeter (Tritech PA500), Transmissometer (Wetlabs CStar), CDOM, Chlorophyll-a, Scattering (Wetlabs ECO FLCDRTD) were installed on the auxiliary A/D channels of the CTD. The collected data were processed (quality-controlled), and subsequently archived by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC). 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 IN2023_V07, titled "SWOT-ACC: smaller scales of the Antarctic Circumpolar Current in a meander south of Tasmania." The voyage took place between November 15, 2023 and December 20, 2023 (AEST), departing from Hobart and returning to Hobart. 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 and other global data repositories and distributors, and made available for satellite SST validation by the Australian Bureau of Meteorology (BoM). Near real-time, unprocessed data are available via the link "Visualisation tool for Underway Data." This dataset has been processed (quality-controlled), and archived by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC). Data are available at time intervals of 5 sec (NetCDF format), 5 sec, 10 sec, 1 min and 5 min (ASCII format). Note: not all variables are quality controlled; please check for existing QC flags in the datasets. Additional information regarding this dataset is contained in the Voyage Summary and/or the Data Processing Reports for this voyage.

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 IN2023_V07, titled: "SWOT-ACC: smaller scales of the Antarctic Circumpolar Current in a meander south of Tasmania." The voyage took place between November 15, 2023 and December 20, 2023 (AEST), departing from Hobart and returning to Hobart. The primary focus of this voyage was to enhance our ability to observe and comprehend the effects of small-scale motions (ranging from 10 to 100 km) on the dynamics of the Antarctic Circumpolar Current (ACC). The groundbreaking Surface Water Ocean Topography (SWOT) satellite mission will provide unprecedented measurements of sea surface height over a wide area with substantially improved spatial resolution compared to traditional altimeters. While SWOT will offer unparalleled coverage in both space and time, it is crucial to obtain in situ subsurface ocean measurements to validate the satellite observations and establish the connection between small-scale variability in sea surface height and subsurface ocean circulation and dynamics. The objective was to gather comprehensive multidisciplinary measurements along a swath traversing a standing meander of the ACC. This meander represents a region of intense eddy activity, cross-front exchange, and vibrant small-scale motions. The experiment's goals encompass characterizing the small-scale variability within this meander, establishing a correlation between small-scale variations in sea surface height and subsurface ocean structure, quantifying the contribution of small-scale processes in facilitating the transport of heat and carbon across the ACC, and investigating the interconnectedness of physical, biogeochemical, and biological processes at small spatial and temporal scales. 5 Triaxus tows were conducted. Pressure, conductivity, temperature, and dissolved oxygen data were gathered from duplicate sensors using a Seabird SBE9plus CTD. Also carried on the Triaxus hull were a cosine Photosynthetically Active Radiation (PAR) sensor, a transmissometer, an ECO Triplet (optical backscatter, CDOM fluorometer and chlorophyll fluorometer), a Laser Optical Plankton Counter (LOPC) and SUNA nitrate sensor. Triaxus hull number 2 was utilized throughout the entire voyage, completing 5 tows with a total towing time of 121.75 hours. The vehicle was generally towed between 5-7 knots depending on the conditions. Overall, it performed well during the entire voyage. The following issues were encountered: • There were 5 instances (Tow1) when the Triaxus software crashing and Seasave stopping. Fortunately, after multiple restarts, it returned to normal operation once payloads and undulations were reset. Additionally, on two occasions, the software failed to maintain the designated undulation schedule and required a restart to execute undulations correctly. • During tow #3, halfway through, the secondary DO sensor #3534 was replaced with #1794. The DOs were in specification however this brought the reading closer together. During the beginning of Tow 3, the Suna data for Triaxus was not displaying on Grafana, leg-2 was thus aborted. • On several of the tows, the fairing became loose from the cable and thrashed in the current. Eventually, the method outlined in IN2023_V06 for securing the fairing was adopted. This involved using regular-sized cable ties and hose clamps spaced approximately 300mm apart along the fairing to keep it securely attached to the sea cable. • During Triaxus tow 4 on December 5th a malware attack was encountered, corrupting the network share drive containing CTD data. The tow was promptly aborted at 0830 UTC, and the vehicle was safely recovered without incident. For more detailed information on the malware attack, please refer to the DAP report. On each tow only data from legs where the Triaxus was vertically undulating regularly were processed. Data from deployment into the water, turns, and retrieval were also gathered but not further processed except to provide surface pressure references for the undulation legs. Pressure, conductivity, temperature, and dissolved oxygen sensor data were converted to calibrated units. Spikes and out-of-range values were removed, and primary sensor data were compared to secondary sensor data. PAR, transmissometer, ECO Triplet and SUNA nitrate data were combined into the dataset. LOPC data was gathered but is not processed or published with this report. Published data have been grouped into 1-decibar bins. Data from the primary CTD sensors were assessed to be more reliable, so the final dataset uses the primary CTD sensor values in the default data variables (i.e., variables without “_2” appended). On this voyage all tows were made up of legs that were sufficiently short to be recorded in single files. As such, a “leg” is the same as a “section” for all tows in this voyage. The published data consist of: • Along-track time-series data for each leg • Synthetic interpolated vertical casts for each undulation peak and trough of each leg • Interpolated sectional plots of various sensor data taken from along-track time-series data for each leg The collected data were processed (quality-controlled), and subsequently archived by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC). Additional information regarding this dataset may be contained in the Voyage Summary and the Data Processing Report.

This record describes the End of Voyage (EOV) data archive from the Marine National Facility (MNF) RV Investigator voyage IN2023_V07, titled "SWOT-ACC: smaller scales of the Antarctic Circumpolar Current in a meander south of Tasmania." The voyage took place between November 15, 2023 and December 20, 2023 (AEST), departing from Hobart and returning to Hobart. For further information please refer to the voyage documentation links. Instruments used and data collected include: Regular measurements: Lowered ADCP (LADCP), Acoustic Doppler Current Profiler (ADCP; 75, 150 KHz ), Greenhouse Gas Analysers (Picarro), Cloud Condensation Nuclei counter (CCN), Condensation Particle Counters (CPC), Disdrometer, Black Carbon Sensor (Aethalometer), Radon sensor, Scanning Mobility Particle Sizers (SMPS), CTD, Hydrochemistry, Triaxus, ECO Triplet, Submersible Ultraviolet Nitrate Analyser (SUNA), Fisheries Echosounder (EK60, EK80), Multibeam Echosounder (EM710, EM122), Sub-bottom Profiler (SBP120), GPS Positioning System, Doppler Velocity Log, Thermosalinographs (TSG), Fluorometer, Oxygen Optode, Infrared Sea Surface Temperature Autonomous Radiometer (ISAR), pCO2, Multiangle Absorption Photometer (MAAP), Ozone Sensor, Nephelometer, Atmospheric Temperature, Humidity, Pressure, Wind and Rain sensors, Photosynthetically Active Radiation (PAR) sensor, Precision Infrared Radiometer (PIR), Precision Spectral Pyranometer (PSP), ITI Trawl Net, Starboard and Portside Radiometers, Air Sampler, Ultra Short BaseLine Underwater Positioning System (USBL), Weather Radar, Expendable Bathythermographs (XBTs). Voyage-specific measurements: Spectral Absorption and Attenuation Sensor (AC-S), Cloud Radar (BASTA), Moorings, Micro Rain Radar (MRR), Stabilised Platform, Water Vapor Radiometer (WVR), Core Argo floats, EM-APEX Floats, Near-surface Drifters, Gliders. The archive for the IN2023_V07 EOV raw data is curated by the CSIRO National Collections and Marine Infrastructure (NCMI) Information and Data Centre (IDC) in Hobart, with a permanent archive at the CSIRO Data Access Portal (https://data.csiro.au/), providing access to voyage participants and processors of the data collected on the voyage. All voyage documentation is available electronically to MNF support via the local network. Applications to access voyage documentation by non-CSIRO participants can be made via data-requests-hf@csiro.au. All processed data from this voyage are made publicly available through the MNF Data Trawler (in the related links).