EARTH SCIENCE > OCEANS > SALINITY/DENSITY > CONDUCTIVITY
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As part of Australian Antarctic Science project # 4298 and Antarctica New Zealand project K131A, integrated biological and physical observations were conducted including these series of CTD measurements. The objective of these measurements is to quantify the oceanographic conditions at our field camp off Davis Station in November-December 2015. In situ CTD measurements at the thermistor and the ROV (Remotely Operated Vehicle) sites were deployed using a Seabird-37SMP-ODO MicroCat CTD. Logistics and environmental constraints permitted measurements for seven casts during our deployment at Davis in 2015. The location of the thermistor site is at (-68.57272 degrees N; 77.93273 degrees E), and the ROV site had its origin (x=0, y=0) at (-68.568904 degrees N,+77.945439 degrees E). The software used was the standard SeatermV2 2.4.1.
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DC Electrical: In order to relate the fluid permeability to the electrical properties of sea ice, we also took measurements of the vertical component of the DC electrical conductivity tensor of sea ice. Cores extending to the bottom of an ice floe were taken and laid out holder. With the exception of sites 7 and 8 where we encountered a slush layer below the hard ice and could not core down to the ocean. The core bottom was determined at sites 7 and 8 to be the ice slush interface. Immediately upon extraction, holes that fit our thermistor probes were drilled every ten centimetres and a temperature profile was taken. Subsequently, slightly larger holes were drilled which fit our electrical probes (stainless steel nails). An AEMC Earth Resistivity Meter was then used to measure the resistance over 10 cm sections of the core (usually offset by 5 cm so that the measured temperature was in the centre of the section where electrical resistance was measured). The cores used in resistance measurements were taken very close to where the crystallographic cores were taken. In almost all cases the cores extracted for electrical measurements were also used for crystallographic analysis, so that there was an exact match of electrical properties with crystal structure. In such cases the DC electrical cores were then moved to a -20 degree C cold room for further processing immediately after measurements in the field. A thin vertical section, approximately 3mm thick, was taken from each of the cores stored for analysis. These sections were placed between a pair of cross polarized plates and photographed. Each photo was labelled with the core and date it was taken, and was photographed with a meter stick alongside for scale. After the thin sections were photographed, the remaining samples were melted to measure salinity. Some of the melted sea ice was saved for later O18 analysis to distinguish samples containing snow ice from those containing marine granular ice. The temperature and salinities we are then used to calculate brine volume fractions along the 10 cm sections of the core. The DC conductivity data collected can be found in the Electrical tab of the Master_Core_List.xls Excel file. The raw data can be found in the scans of our field note books located in the folder named notebooks. In the spread sheet the measured resistances of the 10 cm sections, temperatures, salinities and corresponding brine volume fractions are listed per core. For each core the supporting crystallography core number can be found in the crystallography column of the spread sheet. The photos of the crystallography cores can be found in the crystallography folder, separated into subfolders labelled with the site and core number, Each photo also contains a tag indicating the core number , site taken , date, and what depth range this covers. Tags may not contain a depth range for cores less than 1 meter. Please see the meter stick in each photo for scale.
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AM01 borehole drilled January 2002 at a height of 65 metres above sea level. Data collected in series of casts over a period of 5 days following completion of borehole. Consult Readme file for detail of data files and formats. A word document providing further information is also available as part of the download. All of the .dat files of data can be viewed with a text editor such as Wordpad.
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Oceanographic measurements conducted on voyage 1 of the Aurora Australis of the 1999-2000 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 1: Polynya study off Mertz Glacier at about 145 deg E. The vessel departed from Port Arthur for the polynya study site without returning to Hobart. The voyage also deployed moorings and delivered biologists (for seal and penguin programs) and a small quantity of essential supplies and mail to Macquarie Island. Leader: Dr Ian Allison Deputy Leader: Dr Tony Worby Cargo Supervisor: Dr Vicky Lytle See the readme files in the downloads for more information.
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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.
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We deployed CTD sensors on five of the SIPEX 2 ice stations for collecting temperature and salinity of the water column under the sea ice. This dataset contains the raw data as outputted from the CTD in Excel format, in English. The dates that the CTD were deployed are in the file names (i.e. 20121023 is October 23, 2012).
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Data were collected during the 1997-1998 austral summer on voyages by the Aurora Australis and Southern Surveyor. Taken from the abstract of the referenced paper: 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. Here we present a brief overview of the SAZ Project and some of its major results, as detailed in the 16 papers that follow in this special section. The Southern Ocean plays an important role in the global oceanic overturning circulation and its influence on the carbon dioxide contents of the atmosphere. Deep waters upwelled to the surface are rich in nutrients and carbon dioxide. Air-sea interaction modifies the upwelled deep waters to form bottom, intermediate, and mode waters, which transport freshwater, oxygen, and carbon dioxide into the ocean interior. The overall effect on atmospheric carbon dioxide is a balance between outgassing from upwelled deep waters and uptake via both dissolution in newly formed waters (sometimes referred to as the solubility pump) and the transport of photosynthetically formed organic carbon to depth in settling particles (referred to as the biological pump). Determining the variations in the overturning circulation and the associated carbon fluxes in the past and their response to increased anthropogenic emissions of carbon dioxide in the future is essential to a full understanding of the controls on global climate. At present the upwelled nutrients are incompletely used. Low light in deep wind-mixed surface layers, lack of the micronutrient iron, and other factors restrict phtyoplankton production so that Southern Ocean surface waters represent the largest high-nutrient, low chlorophyll (HNLC) region in the world.
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Metadata record for data from ASAC Project 1101 See the link below for public details on this project. ---- Public Summary from Project ---- Most of our knowledge of the Antarctic marine ecosystems comes from summer surveys. There are very few observations of this ecosystem in winter and there is a fundamental lack of knowledge of understanding of even basic questions such as 'what is there?' and 'what's it doing?'. The proposed visit to the sea ice zone in winter is a rare opportunity to conduct observations on phytoplankton, krill, birds, seals and whales, so that we can begin to understand the biological processes that go on in winter. Data for this project were intended to be collected on a 1998 winter voyage of the Aurora Australis, but a fire on board meant that the voyage had to return to port before work could be carried out. Data were then collected the following year during a 1999 winter voyage of the Aurora Australis (IDIOTS), which ran from July to September. Data attached to this metadata record, include zooplankton and CTD data collected from the Mertz Glacier region. The data have been compiled by Angela McGaffin, and can be found in the "processed" folder of the download file. Original datasets are also available in the "Original Datasets" folder.
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This indicator is no longer maintained, and is considered OBSOLETE. INDICATOR DEFINITION Measurements of sea surface salinity in the Southern Ocean. Measurements are averaged over latitude bands: 40-50 deg S, 50-60 deg S, 60 deg S-continent. TYPE OF INDICATOR There are three types of indicators used in this report: 1.Describes the CONDITION of important elements of a system; 2.Show the extent of the major PRESSURES exerted on a system; 3.Determine RESPONSES to either condition or changes in the condition of a system. This indicator is one of: CONDITION RATIONALE FOR INDICATOR SELECTION Australian and Antarctic climate and marine living resources are sensitive to the distribution of ocean salinity. Sea surface values are relatively easy to monitor, and therefore can be used as a relevant indicator of the state of the ocean environment. The information provided by long records of sea surface salinity is needed to detect changes in the Southern Ocean resulting from climate change; to test climate model predictions; to develop an understanding of links between the Ocean and climate variability in Australia; and for sustainable development of marine resources. DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM Spatial scale: Southern Ocean: 40 deg S to the Antarctic continent Frequency: Monthly averages over summer Measurement technique: Measurements of sea surface salinity from Antarctic supply ships. RESEARCH ISSUES Sea surface salinity has not been previously used as a spatially averaged environmental indicator. Some experimentation with past data are required to define the most appropriate averaging strategy. New technologies like profiling Argo floats need to be exploited to provide better spatial and temporal coverage of salinity in the Southern Ocean. LINKS TO OTHER INDICATORS Sea surface temperature Sea ice extent and concentration Chlorophyll concentrations concentrations
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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.