RV Investigator Voyage IN2021_V04 CTD Data

This record describes the Conductivity-Temperature-Depth (CTD) data collected from the Marine National Facility RV Investigator voyage IN2021_V04, titled: "Biodiversity Assessment of Australia’s Indian Ocean Territories." The voyage took place between June 30 and July 29, 2021 departing from Darwin (NT) and arriving in Hobart (TAS).

Data for 25 deployments were acquired using the Sea-Bird SBE911 CTD 24, fitted with 31 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 0.0013062 PSU, within our target of ‘better than 0.002 PSU’. The standard product of 1 decibar binned averaged were produced using data from the primary sensors.

The dissolved oxygen data calibration fit had a SD of 0.089089μM. The agreement between the CTD and bottle data was good.

There was an observed spike in values indicating a blockage in the secondary sensors of CTD deployment 11 around 2700 decibar and it is recommended to use the primary sensor data.

An Altimeter, Nephelometer, Transmissometer, CDOM, Fluorometer, and Turbidity meter were also installed on the auxiliary A/D channels of the CTD. The Seapoint nephelometer values were found to be out of the expected range for the sensor.

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.