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EARTH SCIENCE > OCEANS > SEA ICE

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  • A numerical model of ocean wave interactions with Antarctic sea ice cover, including: (i) attenuation of wave energy due to the ice cover (based on the empirical model of Meylan, Bennetts, Kohout, 2014, Geophys Res Lett, doi:10.1002/2014GL060809); and (ii) breakup of the ice cover into smaller floes due to strains imposed by wave motion (based on the theory of Williams et al, 2013, Ocean Model., doi:10.1016/j.ocemod.2013.05.010). The model is coded in FORTRAN90 for use as a module in a standalone version of the CICEv4.1 sea ice model (http://oceans11.lanl.gov/trac/CICE). It requires incident wave forcing to be specified at some constant latitude outside the ice cover, which can be user chosen or imported from data files (e.g. data given by Wavewatch III hindcasts, see http://doi.org/10.4225/08/523168703DCC5). Modifications to the existing CICE routines are given to allow integration of the broken floe sizes into its lateral melting scheme, and for incorporation of a floe bonding scheme. Bennetts, O'Farrell and Uotila (submitted) use the model to study the impact of wave-induced ice breakup on model predictions of the concentration and volume of Antarctic sea ice.

  • Pulse Amplitude Modulation (WaterPAM, Walz) was used to measure the response of the sea ice brine microalgae to CO2 stress. All data was reported in WinControl software and follows standard formats. Three incubation experiments were carried out at SIPEX stations 4 (expt 1) 7 (expt 3) and 8 (expt 4). File nomenclature TO: time zero TR1,2,3 refers to times 2,3 and 4 respectively In expt 4 the coding refers to hours since beginning of experiment Each file contains data in the same columns: Important results include Column E: F Column F: Fm Column G: Fv/Fm Column H: rETR Column I: PAR

  • Two Waves In Ice Observation Systems (Kohout, Alison L., Bill Penrose, Scott Penrose, and Michael J M Williams. 2015. “A Device for Measuring Wave-Induced Motion of Ice Floes in the Antarctic Marginal Ice Zone.” Annals of Glaciology 56 (69): 415–24. doi:10.3189/2015AoG69A600) were deployed about 1.5 km apart on ice floes close to latitude 62.8 S and longitude 29.8 E on 4th July 2017 (NYU1 and NYU2). The region where the instruments were deployed (Antarctic Marginal Ice Zone) consisted of first-year ice on average 40 – 60 cm thick. The instruments were deployed by hand by three people, lowered by crane from the ship to the ice on a basket cradle. NYU 1 was deployed on a rectangular ice floe of length 8 m and width 3 m, with a thickness of about 40 – 50 cm. NYU 2 was deployed on a triangular ice floe of length 4 m and thickness 40 cm. The temporal resolution is variability (every 15 minutes to 2 hourly). The survival of the sensors depended on staying fixed to the floe and the battery life. On 12th July, the sampling rate of NYU 2 was reduced from 15 minutes to 2 hourly to extend the battery life. On 13th July, NYU 1 overheated and the battery dropped below the operating voltage. NYU 2 continued to send back data for another six days, but then stopped sending data for an unknown reason on 19th July. Records can support 1. the assessment of metocean conditions in the Southern Oceans; and 2. calibration and validation of wave and global circulation models.

  • Chlorophyll data was used to measure growth rates of sea ice algae in CO2 incubations. Sea ice brine microalgae was collected from sackholes. Replicate samples were incubated in ambient air (~0.04% CO2), 0.1% CO2, 1.0% CO2 and 2.0% CO2 concentrations. AT the end of the incubations the 50 ml samples were filtered through a 25 mm GF/F filter using vacuum filtration. The filters were placed in 15 ml plastic falcon tubes containing 10 ml of methanol, covered in aluminium foil and kept in the dark at 4 degrees C for 12 hours. Chl a concentration was measured using a 10AU Turner fluorometer following the acidification method of Strickland and Parsons (1972). Data in spread sheet shows the extracted chl + phaeophytin, phaeophytin and chlorophyll concentrations (micro grams l-1) for each of the three experiments. Data were collected at SIPEX Ice Stations 1-8 and SIPEX CTD stations 2-5

  • Between 1954 and 1975, iceberg observations were collected on Australian National Antarctic Research Expeditions (ANARE) by Antarctic expeditioners on a volunteer basis as they travelled to and from Antarctica. No fixed format for data collection had been determined, and many of the observations recorded are in diary format. The data have not been converted to electronic form, and are available only in the original logbooks held at the National Archives Office.

  • 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.

  • Metadata record for data expected from ASAC Project 2767 See the link below for public details on this project. A multidisciplinary survey of the processes linking sea ice with biological elements of Antarctic marine ecosystems was conducted in winter 2007. The survey provided large-scale information on sea ice biological and physical parameters in the 100-130 degree East sector off East Antarctica. The distribution of sea ice algae and krill were measured using various methods including ice coring surveys and trawls. These measurements were complemented by shipborne measurements and an intensive sea ice sampling program. Use of an ROV was attempted but did not result in quantitative/geo-referenced data. Under-ice video files are available from the Chief-Investigator. Individual word documents are available from this metadata record for each ice station. These contain information on the ice station number, date and time of record and the parameters/ samples.

  • During voyage 1 of 1985, sixteen ice cores were drilled from sea ice. Details from those cores include the position they were drilled, length of the core, percentage of the core that was frazil ice, and comments on the state of the core, or observations of the ice make-up. Physical records are archived at the Australian Antarctic Division.

  • Observations of the sea ice cover at Wilkes base in Autumn-Winter 1963. Includes water temperature, air temperature, wind speed and direction, cloud cover, relative humidity, and general notes. These documents have been archived at the Australian Antarctic Division.

  • This dataset contains data relating to an experimental method in which sea-ice samples were measured in an S-band microwave waveguide. This was conducted as a part of the 2012 SIPEX 2 (Sea Ice Physics and Ecosystems EXperiment) marine science voyage. A specially designed waveguide apparatus was connected to an Agilent FieldFox Portable Network Analyzer. Small parallelopipeds (7 cm X 3 cm X 1.9 cm) of sea ice were cut with a hand saw in a specially designed jig which holds an initially cylindrical core. The samples were placed at the end of the waveguide, configured to measure the vertical component of the effective complex permittivity tensor, and microwaves of frequency 2.9 GHz were sent down the tube. The samples were sized precisely to fit snugly in the end of the waveguide in order to minimize spurious reflections. The FieldFox recorded the coefficients of the scattering matrix, from which the complex permittivity can be computed. Sample temperature was taken both before and immediately after insertion into the waveguide. In order to assess the presence of off-vertical components of the electromagnetic field and how they may affect the measurements, a second sample was prepared with an orthogonal orientation, adjacent to the first sample. The same microwave measurements were taken on the second sample, to be later correlated with those from the first sample. The samples were stored in the freezer for later crystallographic analysis, and subsequently melted for salinity measurements. Prior to melting the samples were measured using callipers to determine their dimensions precisely. Samples were measured along each face at their minimum and maximum point for their width in the direction of propagation. In most cases samples were measured in all dimensions for better error analysis. A thin vertical section, approximately 5mm thick, was taken from each microwave sample stored for analysis. These sections were placed between a pair of cross polarized plates and photographed. Photos of the crystallography cores can be found in the crystallography folder, in a sub folder titled microwave. Each photo also contains a tag indicating the core number, site taken, date, as well as a V or an H indicating whether the sample was used for measurement of the vertical (V) or off-vertical (H) response. The scattering parameters recorded by the Field Fox can be found in the Data folder. Each file is named according to the microwave core measurement it represents and whether the measurement was of the vertical (V) or off-vertical (H) response. Each contains a standard S11 scattering parameter, stored as a comma separated value (CSV) file. Raw data can be found in the raw folder, and data that has been processed for ease of Matlab import can be found in the Reformatted_for_matlab folder. This processing involves taking output data that by default has four entries in a single column vector and remapping the data to create a four column matrix, each with a single entry. Recorded values for each microwave sample can be found in the Master_Core_List.xls Excel spreadsheet, within the Microwave worksheet. This worksheet was generated directly from notebook data, and contains the date, core number, depth of interface between the two collected samples, the minimum, maximum, and average thickness along the axis of propagation, The recorded temperatures from before and after measurement, the salinity, and calculated brine volume fraction. Finally, the worksheet contains notes, and a column to indicate whether we believe this data is somehow bad. Measurement information for thicknesses along other axis than that of propagation can be found in notes, but this data may at some stage be incorporated into a separate column. Please see the notes section for reasons why a data point was determined invalid. Typically this was due to the corresponding sample breaking while cutting into the parallelepiped shape. Scans of the original notebooks containing measured salinity values, thicknesses, and temperatures from which the Permeability worksheet were created are provided in the notebooks directory.