The Animal Tagging Sub-Facility of the IMOS Animal Tracking Facility (formerly known as the Australian Animal Tracking And Monitoring System (AATAMS)) is a coordinated marine animal satellite-tracking project. Satellite Relay Data Loggers (SRDL) (most with Conductivity-Temperature-Depth (CTD) sensors, and some with CTD/fluorometers) are used to explore how marine animals (e.g. mammals) interact with their oceanic environment. The primary focus of this program is to collect CTD data from marine mammals, such as southern elephant seals (Mirounga leonina) and Weddell seals (Leptonychotes weddellii), in the southern Indian Ocean and along the East Antarctic coast. This is achieved through international collaborations with the French national polar program?s long-term National Observatory Services: Mammals as Ocean Bio-Samplers (SNO-MEMO), the National Institute of Water and Atmospheric Research as part of the Ross Sea Research and Monitoring Programme, and the CNES (Centre National d'Etudes Spatiales) TOSCA programme (Phoques de Weddell bio-oc?anographes de la banquise antarctique et outils satellites) in Terre Ad?lie. SRDL loggers developed at the Sea Mammal Research Unit (SMRU, University of St Andrews, UK) transmit data in near real time via the Argos satellite system. This metadata record, represents several different datasets listed hereafter, which can all be accessed through a multi-WFS service.
The data represented by this record are presented in delayed mode.
CTD - parameters measured by the instruments include time, depth, conductivity (salinity), temperature, speed and fluorescence (available in some deployments).
Diving ? parameters measured by the instruments include individual dive start and end time, longitude/latitude at dive end time, post-dive surface duration, dive duration, maximum dive depth, intermediate dive depths and times.
Haulout - a haulout begins when the SRDL has been continuously dry for a specified length of time (usually 10 minutes). It ends when continuously wet for another interval (usually 40 seconds). Haulout data parameters measured by the instruments include haulout start and end dates and longitude/latitude, and haulout number.
Argos Locations - location data parameters measured by the instruments include time, longitude, latitude, location quality, along with other diagnostic information provided by Argos (http://www.argos-system.org/).
Summary Statistics - as well as sending records of individual events such as dives and haulouts, the SRDL also calculates summary statistics of those events over a specified time period (usually 3, 4 or 6 hours). Summary statistics computed by the instruments include the proportion of time spent diving, at the surface and hauled-out, the number of dives, and the average, standard deviation and maximum dive duration and dive depth during each summary period. These statistics are based on all the data recorded by the SRDL and thus are not prone to distortion by variations in the efficiency of transmission via Argos.
SSM QC Locations - SSM-predicted locations and uncertainty at 6-h intervals from the location quality-control process. SSM-predicted locations are also appended to records in the CTD, Diving, Haulout, Argos Locations, and Summary Statistics datasets. See Jonsen et al. 2020 for further details on the SSM used for location quality control.
** For data prior to October 2018, please consult IMOS - Animal Tracking Facility - Satellite Relay Tagging Program - Delayed mode data (https://catalogue-imos.aodn.org.au:443/geonetwork/srv/api/records/06b09398-d3d0-47dc-a54a-a745319fbece), to access data without improved satellite locations. In the near future all historical delayed mode data will be reprocessed with the new quality control (QC) process, to improve the accuracy of the satellite location data, and this dataset will replace the original one. **
Maintenance and Update Frequency: asNeeded
Statement: Animal Tracking Facility SRDL logger data have been supplied to IMOS by Animal Tagging Sub-Facility participants, via the Sea Mammal Research Unit (SMRU, St Andrews University, UK). Tags used on southern elephant seals and Weddell seals - CTD Oceanography Satellite Relay Data Loggers (Argos) - collect conductivity, temperature and depth information. On some seals - CTD/Fluorometer Oceanography SRDL (Argos) - collect conductivity, temperature, fluorescence and depth information. The CTD Oceanography SRDL (Argos) and CTD/Fluorometer Oceanography SRDL (Argos) are built by SMRU and incorporate CTD sensors developed by Valeport Ltd (Devon, UK) and a Turner Cyclops-7 fluorometer sensor developed by Turner Designs (San Jose, US). The CTD 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 +/- 0.01 mS/cm, respectively. Before being taken into the field, devices are calibrated in the laboratory by Valeport. CTD-SRDLs and CTD/Fluorometer 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.
When all deployments in a year have completed, the Animal Tagging Sub-Facility will conduct delayed-mode QC on the ARGOS positions and hydrographic (CTD) profile data. ARGOS geo-positioning is inherently error-prone, even with the introduction of new geo-positioning algorithms in 2011. The Animal Tagging Sub-Facility uses a state-space model to quality control Argos location data, providing a median accuracy of +/- 3.24 km; see Jonsen et al. (2020) for details. These quality-controlled geo-positions are appended to all datasets (prefix: ?qc_ssm_?) and also provided as a separate dataset, SSM QC Locations, where SSM-predicted locations and their uncertainty are provided on a regular 6-h time interval. 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 55?S) 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 ?C 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 ?C and ?0.1 psu.
Integrated Marine Observing System (IMOS). IMOS is a national collaborative research infrastructure, supported by Australian Government.
Sydney Institute of Marine Science (SIMS)
French National Center for Scientific Research (CNRS)
University of Tasmania (UTAS)
Australian Antarctic Division (AAD)
National Institute of Water and Atmosphere (NIWA)
CSIRO Oceans and Atmosphere
Stockholm University (SU)
Shanghai Ocean University