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  • Oceanographic processes in the subantarctic region contribute crucially to the physical and biogeochemical aspects of the global climate system. To explore and quantify these contributions, the Antarctic Cooperative Research Centre (CRC) organised the SAZ Project, a multidisciplinary, multiship investigation carried out south of Australia in the austral summer of 1997-1998. Taken from the abstracts of the referenced papers: The SAZ project organised by the Antarctic CRC has a continuing program of moored sinking particle trap studies in the Aub-Antarctic and Polar Frontal zones southwest of Tasmania along 140 degrees E. The first deployment obtained weekly or higher resolution samples through the austral summer from September 1997 through February 1998 at three locations: the central Sub-Antarctic Zone (47 degrees S, traps at 1000, 2000 and 3800 m depth), the Sub-Antarctic Front (51 degrees S, 1 trap at 3300 m) and above the Southeast Indian Ridge in the Polar Frontal Zone (54 degrees S, 2 traps at 800 and 1500 m). The particles were analysed for total mass, inorganic carbon, total carbon, nitrogen, silicon, and aluminium. Hence values for organic carbon, biogenic silica, and lithogenics were obtained, and the mass fluxes calculated. This report details the sites, moorings, data from the current meters and sediment traps, and results of analyses performed on the collected sediment trap material. Sediment trap moorings were deployed from September 21, 1997 through February 21, 1998 at three locations south of Australia along 140 degrees E: at -47 degrees S in the central Subantarctic Zone (SAZ) with traps at 1060, 2050, and 3850 m depth, at-51 degrees S in the Subantarctic Front with one trap at 3080m, and at -54 degrees S in the Polar Front Zone(PFZ) with traps at 830 and 1580m. Particle fluxes were high at all the sites (18-32gm-2 yr-1 total mass and 0.5-1.4g organic carbon m-2 yr-1 at ~1000m, assuming minimal flux outside the sampled summer period). These values are similar to other Southern Ocean results and to the median estimated for the global ocean by Lampitt and Antia [1997], and emphasise that the Southern Ocean exports considerable carbon to the deep sea despite its "high-nutrient, low chlorophyll" characteristics. The SAZ site was dominated by carbonate (greater than 50% of total mass) and the PFZ site by biogenic silica (greater than 50% of total mass). Both sites exhibited high export in spring and late summer, with an intervening low flux period in December. For the 153 day collection period, particulate organic carbon export was somewhat higher in all the traps in the SAZ (range 0.57-0.84 gC m -L) than in the PFZ (range 0.31-0.53), with an intermediate value observed at the SAF (0.60). The fraction of surface organic carbon export (estimated from seasonal nutrient depletion, Lourey and Trull [2001]) reaching 1000 m was indistinguishable in the SAZ and PFZ, despite different algal communities.

  • Metadata record for data from ASAC Project 2784 See the link below for public details on this project. This project utilised an existing 55 year model reanalysis (SODA) - so no new models were developed. The methodologies/data used are described in the referenced publications. Modelling investigations of the shoaling of iron-rich upper circumpolar deep water (UCDW) and its role in the regulation of primary production at 60-65S. Taken from the project application: We intend to utilise a number of existing data sources to study the factors leading to spatiotemporal variability in the upwelling of iron-rich UCDW in the 60-65S zone, which, as discussed above, seems critical to regional ecosystem function, and the carbon and sulphur budgets of the SO. As sea-ice extent appears to have declined in the Southern Ocean since the 1950s (Curran et al., 2003) it will also be extremely interesting to examine whether this has had any affect on the upwelling of the UCDW. Given the restricted spatial domain of in situ field data in the Southern Ocean, satellite products provide us with one of the few means to investigate coherent variability over large spatial and temporal scales. This study takes advantage of our previous AAS funded work (Projects: 2584, 2319), where we have gained considerable experience in the coupling of biogeochemical and climate models and where we have already assembled satellite data sets on wind speed, sea-ice, SST, aerosols and chlorophyll-a concentration. This previous experience will allow us to examine the relationship between the physical forcings, the dynamics of the UCDW and the biological response on seasonal and interannual timescales over the period 1950-2000. The key scientific questions we seek to answer include: - What is the range of interannual and interdecadal variability in upwelling of the UCDW and how does this relate to variability in primary production? - Is there a connection between interannual/decadal variability in sea-ice extent and the strength or location of upwelling of UCDW and hence the character of regional primary production? - Is there a relation between the seasonal production of DMS and associated S-aerosols and the dynamics of UCDW? Details from previous years are available for download from the provided URL. Taken from the 2009-2010 Progress Report: Progress against objectives: This three-year project has been investigating the nexus between the large-scale meridional circulation patterns in the SO, in particular UCDW upwelling, and concomitant iron delivery to surface waters and the phytoplankton. Key Scientific Questions to be considered by the project What is the range of interannual and inter-decadal variability in upwelling of the UCDW and how does this relate to variability in primary production? This study initially focussed on the Australian region of the Southern Ocean (110-160 degrees S, 40-70 degrees E) and the physical oceanographic data for the project came from monthly Simple Ocean Data Assimilation (SODA) reanalysis data, which covers the period 1958-2007 over the global ocean. Decadal-scale trends in upper ocean structure and meridional circulation were analysed, including the upwelling of nutrient-rich UCDW, and these results were initially documented in presentation (3) below and will shortly be published in publication (1) listed below. The project identified UCDW in SODA using temperature and density criteria and, using this, a number of variables were developed to characterise UCDW and its upwelling: UCDW vertical velocity, temperature, density and salinity, UCDW top depth (the shallowest depth at which UCDW is found) and UCDW southern-most position. Climatological values were found for each of the 5-degree strips in the sector and, in addition, trends were found over the period 1958-2005. Later work involved comparing these results with those of two more Southern Ocean sectors - one in the Pacific (130-80 degrees W) and one in the Indian Ocean (20-60 degrees E). These results were presented at the AMOS conference in January 2010 (see Presentation (1) below) and are also the subject of a paper in the Proceedings of that conference (see Publication (2) below). It was found that during 1958-2005: (1) UCDW top depth varies seasonally, peaking in March, and displays considerable interannual variability; (2) Climatological properties for UCDW variables such as temperature, vertical velocity and upwelling depth vary between the three ocean sectors, as do trends (1958-2005) in the UCDW variables; (3) UCDW vertical velocity (ie. upwelling) appears to be increasing with time in most intermediate and deep waters of the three ocean sectors; (4) UCDW temperature is increasing in intermediate waters in the Pacific sector, at all depths in the Indian sector and at shallow depths in the Australian sector, but is decreasing in intermediate and deep waters in the Australian sector; (5) UCDW southern-most position is moving south in the Australian and Pacific sectors; (6) UCDW is upwelling closer to the surface in the Australian and Indian sectors and, in the case of the Australian sector, this translates into an increase in the number of times that UCDW can be detected in the mixed layer (a finding of possible importance for primary production); (7) UCDW trends in the Australian sector do not appear to be affected by trends in the winds, but by forcings acting on longer than decadal time-scales. This is not the case, however, for the other two sectors, leading to the speculation that these variables may be affected by the re-entry into UCDW of recirculated waters from the Indian and Pacific Oceans, which may themselves be affected by winds. (8) The Australian sector of the SO has been shown to have its own unique characteristics, distinct from either the Pacific or Indian sectors. More recent work has involved looking at the initial Australian sector considered above, over the period of the high resolution satellite data capture era (1997-2007), with the aim of using satellite data on chlorophyll a (chl a), sea-ice concentration and photosynthetically active radiation (PAR), as well as modelled data for primary production (PP), in addition to the reanalysis data, to look at factors that influence chl a and PP over that time period. Initial work was presented at the AMOS conference in January 2009 (see Presentation (2) below) and final work is reported in Publication (3) listed below, which is almost ready for submission. It was found that in the Australian sector during 1997-2007: (1) The most important controls on chl a in spring are sea-ice concentration and PAR in the southern-most zones (and mixed layer depth, SST, stratification and PAR in zones further north); (2) The situation is more complex in summer, especially in the southern-most zones (the areas of highest production, excluding the most northerly zone near Tasmania). In particular, in the 60-65 degrees S zone in summer, a variety of inter-acting controls affect chl a (and PP), including SST, stratification and UCDW top depth; (3) The number of times that UCDW is detected in the mixed layer is decreasing in summer during 1997-2007; (4) It is difficult to identify trends that are statistically significant over such a short time period and trends that are found are often opposite in sign to those for 1958-2005 and up to an order of magnitude larger. Thus care needs to be taken with trends found for chl a, PP and hydrodynamic variables over the short period of the satellite era, since there is a large range of such ten-year trends in the period 1958-2005. Is there a connection between interannual/decadal variability in sea-ice extent and the strength or location of upwelling of UCDW and hence the character of regional primary production? Given that UCDW upwells south of the Polar Front and no further south than the Southern Boundary of the ACC (approximately 65 degrees S in this sector), then UCDW, as identified here in its pure form, is not able to affect the 65-70 degrees S zone (although this is possible in its modified form, which is not studied here). It was found that, for the period 1997-2007 in the Australian sector of the SO, the southern-most position of UCDW is not correlated with sea-ice concentration, but that there are weak (90% level) correlations in 60-65 degrees S between UCDW top depth and sea-ice concentration in autumn (positive), the temperature of UCDW and sea-ice concentration in summer (positive) and northward Ekman transport and sea-ice concentration in summer (negative). It was found that, for 1997-2007 in the Australian sector of the SO, sea-ice concentration has a significant (inverse) relationship with chl a and PP in 60-70 degrees S in spring and 65-70 degrees S in summer. In addition, UCDW top depth and northward Ekman transport (ie. how quickly the UCDW nutrients are transported northwards and away from the zone) have a minor effect on chl a in 60-65 degrees S in summer.

  • AM01 borehole drilled January 2002 at a height of 65 metres above sea level. Current meter data dips collected during routine CTD operations over a period of 4 days upon completion of borehole. Consult Readme file for detail of data files and formats.

  • In situ Lagrangian drifter positions were collected from nine expendable sea-ice buoys. Positions were collected by GPS receivers aboard each buoy and relayed via the CLS Argos satellite data system. The scientific proposal for this project was based on the deployment of two meso-scale buoy arrays over the continental shelf break in the SIPEX 2012 experimental region. Resolving of ice motion over the continental shelf and the shelf break is expected to provide crucial information on sea-ice deformation and ice strength. However, due to the unfavourable cruise track and also due to operational issues with helicopter support, it was not possible to deploy any of the meso-scale buoy arrays. Instead buoys were deployed to resolve ice deformation within the wider SIPEX 2012 region. Position data are available hourly from most buoys. CLS Argos transmitted data suffer from a data transmission blackspot just prior to local none, when there will be no data available. Data processing will be carried out as described in Heil et al. [2008] The dataset is build from ASCII files for each buoy with time stamps and observed latitude and longitude. The format (by column [C] for each file is as following: C1: Program ID C2: Buoy ID C3: Year C4: Month C5: Day C6: Hour C7: Minute C8: Second C9: Day-of-year C10: Lat (degN) C11: Lon (degE)

  • Acoustic Doppler current profiler (ADCP) measurements from a hull mounted 150 kHz narrow band ADCP unit were collected in the Southern Ocean from 1994 to 1999, on the following cruises: au9404, au9501, au9604, au9601, au9701, au9706, au9807 and au9901. The fields in this dataset are: Currents bottom depth cruise number ship speed time velocity GPS

  • Oceanographic measurements conducted on voyage 6 of the Aurora Australis of the 2000-2001 season. These data comprise CTD (Conductivity, Temperature and Depth) and ADCP (Acoustic Doppler Current Profiler) data. These data were collected by Mark Rosenberg. This metadata record was completed by AADC staff when the data were discovered bundled with acoustics data during a data cleaning exercise. Basic information about voyage 6: The voyage will complete a range of Marine Science activities off the Mawson Coast, and off the Amery Ice Shelf before calling at Davis to retrieve summer personnel and helicopters prior to returning to Hobart. Science equipment calibration will be undertaken at Mawson. (Marine Science activities were interrupted when the Aurora Australis was required to provide assistance in the Polar Bird's attempt to reach Casey, complete the station resupply and return to open water.) Leader: Dr Graham Hosie Deputy Leader: Mr Andrew McEldowney See the readme files in the downloads for more information.

  • Current meter S4_211b is one of four current meters deployed off the coast of Casey Station, Australian Antarctic Territory. S4_211a was located in Shannon Bay at 66 degrees 16.727 minutes South, 110 degrees 31.434 minutes West. Further deployment details can be found in the 'Mooring Details' section of the data, as well as a 'Location Map'. The data includes: current speed components, current speed and current direction, a progressive vector diagram of displacement, and water temperature. The data were recorded by the Australian Antarctic Division, and processed by Oceanographic Field Services Pty Ltd. Data was recorded between 3:30am 18 November 1997 (GMT) and 7:30am 29 December 1998 (GMT). The fields in this dataset include: Date Time Speed (centimetres per second) Direction (degrees) Temperature (degrees)

  • Marine debris records from beaches on Heard and Macquarie Islands and floating debris spotted on voyages. Data were collected by observers surveying beaches either methodically or opportunistically, and by observers spotting debris as it floated past ships. The data were originally collated into a searchable database, but the application is no longer supported by the Australian Antarctic Data Centre. An extract of the data is attached to this metadata record. The extract is in Excel format, and each worksheet is a copy of a database table.

  • Current meter S4_212b is one of four current meters deployed off the coast of Casey Station, Australian Antarctic Territory. S4_211a was located in Shannon Bay at 66 degrees 16.727 minutes South, 110 degrees 31.434 minutes West. Further deployment details can be found in the 'Mooring Details' section of the data, as well as a 'Location Map'. The data includes: current speed components, current speed and current direction, a progressive vector diagram of displacement, and water temperature. The data were recorded by the Australian Antarctic Division, and processed by Oceanographic Field Services Pty Ltd. Data was recorded between 3:30am 18 November 1997 (GMT) and 7:30am 29 December 1998 (GMT). The fields in this dataset include: Date Time Speed (centimetres per second) Direction (degrees) Temperature (degrees)

  • Oceanographic measurements conducted on voyage 7 of the Aurora Australis of the 2001-2002 season. These data comprise CTD (Conductivity, Temperature and Depth) and ADCP (Acoustic Doppler Current Profiler) data. These data were collected by Mark Rosenberg. This metadata record was completed by AADC staff when the data were discovered bundled with acoustics data during a data cleaning exercise. Basic information about voyage 7: Subject to ice conditions, the voyage will undertake a range of Marine Science activities in the Prydz Bay area and will retrieve summer personnel, helicopters and limited RTA cargo from Davis station. Leader: Mr Rob Easther Deputy Leader: Ms Gerry Nash See the readme files in the downloads for more information.