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RAN CTD Profile Data - HMAS MERMAID ProjectID: HI542MER_M From: 2013-08-23 To: 2013-10-17

Created 12/03/2025

Updated 12/03/2025

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This dataset contains quality controlled vertical profiles of pressure, temperature and salinity measured by a Conductivity, Temperature and Depth (CTD) probe. The dataset contains 46 CTD profiles (casts) obtained during RAN Hydrographic Survey cruise HI542MER_M from HMAS MERMAID. The CTD was manufactured by Applied Microsystems Limited and is the "Micro CTD" model. This CTD type is referred to operationally as the MVP200_CTD. This CTD is fitted with a 4 electrode platinized conductivity cell, thermistor temperature sensor and a semiconductor strain gauge pressure sensor. The CTD sensors are calibrated at the manufacturer Applied Microsystems Limited on a 12-18 month schedule. The CTD temperature sensor is calibrated against 'Hart' temperature standards. The pressure sensor is calibrated using 'Budenburg Deadweight' standards. The conductivity sensor is calibrated using 'Hart' temperature standards and seawater samples of known conductivity. The CTD sensors are mounted to a fish-shape probe. The probe is controlled by an electric winch (MVP200 type). For downcasts the fish is allowed to free-fall (winch is in 'free-wheel' mode) under its own weight at about 2-3 ms-1 and then is winched back. Data is recorded in downcast and usually in upcast direction at a sampling rate of 25 Hz. The downcast data is of higher quality because sensors encounter undisturbed seawater that flows through the nose of the fish. On the upcast the fish is flipped around (tail first) and the sensors in the nose encounter disturbed flow from the fish tail. This type of CTD is prone to a phenomenon called 'salinity spiking' caused by a mismatch between the response times of the temperature and conductivity sensor. Data undergoes a salinity de-spiking routine to correct for this. See the history metadata for further details on the salinity de-spiking process. Raw CTD pressure data is not always monotonic due to transient up/down motion of winch/ship. Raw pressure data is subsetted to give a monotonic (increasing) sequence and then linearly interpolated to 1 decibar pressure intervals. Data is then flagged with quality control flags after visual inspection and comparison to average climatology and historical CTD casts.

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Additional Info

Field Value
Title RAN CTD Profile Data - HMAS MERMAID ProjectID: HI542MER_M From: 2013-08-23 To: 2013-10-17
Language eng
Licence notspecified
Landing Page https://devweb.dga.links.com.au/data/dataset/7371aad6-3116-48ae-ac69-1b9e6954da81
Contact Point
CSIRO Oceans & Atmosphere
info@aodn.org.au
Reference Period 23/08/2013 - 18/10/2013
Geospatial Coverage {"type": "Polygon", "coordinates": [[[149.33175, -10.79106], [151.79993, -10.79106], [151.79993, -9.04861], [149.33175, -9.04861], [149.33175, -10.79106]]]}
Data Portal data.gov.au

Data Source

This dataset was originally found on data.gov.au "RAN CTD Profile Data - HMAS MERMAID ProjectID: HI542MER_M From: 2013-08-23 To: 2013-10-17". Please visit the source to access the original metadata of the dataset:
https://devweb.dga.links.com.au/data/dataset/ran-ctd-profile-data-hmas-mermaid-projectid-hi542mer_m-from-2013-08-23-to-2013-10-17