The Animal Tracking Facility (formerly known as the Australian Animal Tracking And Monitoring System (AATAMS)) is a coordinated marine animal tagging project. Satellite Relay Data Loggers (SRDL) (most with CTDs, and some also with fluorometers) are used to explore how marine mammal behaviour relates to their oceanic environment. Loggers developed at the University of St Andrews Sea Mammal Research Unit transmit data in near real-time via the Argo satellite system. The Satellite Relay Data Loggers are deployed on marine mammals, including Elephant Seals, Weddell Seals, Australian Fur Seals, Australian Sea Lions, New Zealand Fur Seals. Data is being collected in the Southern Ocean, the Great Australian Bight, and off the South-East Coast of Australia. Data parameters measured by the instruments include time, conductivity (salinity), temperature, and depth. The data represented by this record are presented in near real-time.
As of the 19/11/2019, this data collection has been decommissioned. Historical files are still available on the IMOS THREDDS catalog.
All subsequent CTD data is available via the current “IMOS - AATAMS Facility - Satellite Relay Tagging Program - Delayed mode data” collection (https://catalogue-imos.aodn.org.au:443/geonetwork/srv/api/records/06b09398-d3d0-47dc-a54a-a745319fbece) in csv format, as opposed to NetCDF as was previously delivered via this “Near real-time” collection.
Maintenance and Update Frequency: asNeeded
Statement: The Animal Tracking Facility make all satellite logger data available in near real-time, with no quality control applied to the data before release. Data available in near real-time is a subset of the full dataset collected by the satellite loggers. Satellite Relay Tag data has been supplied to IMOS by participants, via the St Andrews University Sea Mammal Research Unit. Tags used on species: Australian Fur Seal, Australian Sea Lion, New Zealand Fur Seal and Southern Elephant Seal - CTD Satellite Relay Data Loggers (SRDL). Collect conductivity, temperature and depth information. On some Australian Sea Lions - CTD/Fluorometer Satellite Relay Data Loggers (SRDL). Collects conductivity, temperature, fluorescence profiles and depth information. Weddell Seals - Satellite Relay Data Loggers (SRDL). Collect temperature, speed and depth information. CTD- SRDLs The CTD–Satellite Relay Data Loggers (CTD-SRDLs) are built by the Sea Mammal Research Unit (SMRU, University of St. Andrews, UK), incorporating CTD sensors developed by Valeport Ltd (Devon, UK). The sensor head consists of a pressure transducer, a platinum resistance thermometer, and an inductive cell for measuring conductivity. The temperature and conductivity sensors have a precision (repeatability) of 0.005°C and 0.005 mS/cm, respectively. Before being taken into the field, devices are calibrated in the laboratory by Valeport. Some of the CTD-SRDLs (about half) were also tested at sea against a ship-based CTD before the deployment. CTD-SRDLs record hydrographic profiles during the ascent of seals, retaining only the deepest dive in each six-hour time interval, and transmitting profiles in a compressed form (between 10 and 25 data points per profile, depending on the tag program) through the Advanced Research and Global Observation Satellite (ARGOS) system. The accuracy of ARGOS geo-positioning is typically better than ±5 km, because seals never stay at the surface more than a few minutes. New methods are currently under development by the ARGOS team, which should substantially improve the quality of positioning. Hydrographic profiles are post-processed using a unified procedure of editing, adjustment, and validation. A standard set of tests, adapted from Argo standard quality-control procedures, is first run to remove bad profiles, spikes, and outliers. For CTD-SRDLs with profiles in frozen areas, a temperature offset was estimated using the local freezing temperature. A salinity adjustment was also estimated, consisting in a pressure dependent linear correction. This bias is mainly induced by an external field effect on the conductivity sensor, which cannot be corrected a priori because it depends on how the tag has been attached on the seal’s head. Adjustments parameters were estimated for each CTD-SRDLs separately by comparisons of salinity measurements with available data in the World Ocean Database. Because the southern ACC region (south of 55ºS) is associated with a large-scale upwelling of circumpolar deep waters near the surface, the salinity at depth is very stable there, with a low natural variability highly suitable for use as a reference. Salinity data cross-comparisons between different CTD-SRDLs were also used to estimate suitable adjustments for CTD-SRDLs having no profiles available in the southern ACC region. Once calibrated, the accuracy of post-processed CTD-SRDL measurements was estimated to be ±0.03oC in temperature and ±0.05 psu (practical salinity unit) or better in salinity for CTD-SRDLs built after 2007. The achieved accuracy is highly dependent upon availability of ship-based CTD comparisons, and the type of water masses sampled during the deployment time. In best cases, an accuracy of ±0.01 ºC and ±0.02 psu can be obtained. Pre-2007 CTD-SRDLs (about 5% of profiles) used an older technology with a poorer accuracy roughly estimated around ±0.1 ºC and ±0.1 psu.
Australia’s Integrated Marine Observing System (IMOS) is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). It is operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent.
Sydney Institute of Marine Science (SIMS)