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EARTH SCIENCE > CRYOSPHERE > SNOW/ICE > SNOW/ICE TEMPERATURE

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  • Direct Numerical Simulation (DNS) was used to study the effect of sloping the ice-shelves on the dissolution/melt rate at the ice-ocean interface. The simulations were done on the HPC Raijin at NCI, Canberra over March 2015 to June 2017. Numerical experiments were carried out over a range of slope angle (5 degrees – 90 degrees) of the ice-shelves measured from the horizon. Turbulent flow field is simulated over the domain length of 1.8 m, (for slope angle greater than or equal to 50 degrees) and 20 m (for slope angle less than or equal to 20 degrees) respectively; the flow-field is laminar otherwise. A constant ambient temperature 2.3 degrees C and salinity 35 psu is maintained throughout the simulations. The DNS successfully resolved all possible turbulence length scales and relative contributions of diffusive and turbulent heat transfer into the ice wall is measured. Data available: Excel file Meltrate_vs_slopeangle_lam_turb.xlsx contains both simulated laminar and turbulent dissolution/melt rate as a function of slope angle along with their analytical values based on laminar and turbulent scaling theory respectively.

  • AM02 borehole drilled December 2000. Partial annual data retrieved for 2001. Complete annual data retrieved for 2002, and 2003. Consult Readme file for detail of data files and formats. New data and readme added July 2006.

  • AM02 borehole drilled December 2000. Consult Readme file for detail of data files and formats. 2011-2012 data may be final data from the unit owing to battery failure. The original project for this dataset was ASAC 1164, but recent data fall under the auspices of project AAS 4096.

  • Direct Numerical Simulation (DNS) was used to study the effect of sloping the ice-shelves on the dissolution/melt rate at the ice-ocean interface. The simulations were done on the HPC Raijin at NCI, Canberra over March 2015 to June 2017. Numerical experiments were carried out over a range of slope angle (5 degrees – 90 degrees) of the ice-shelves measured from the horizon. Turbulent flow field is simulated over the domain length of 1.8 m, (for slope angle greater than or equal to 50 degrees) and 20 m (for slope angle less than or equal to 20 degrees) respectively; the flow-field is laminar otherwise. A constant ambient temperature 2.3 degrees C and salinity 35 psu is maintained throughout the simulations. The DNS successfully resolved all possible turbulence length scales and relative contributions of diffusive and turbulent heat transfer into the ice wall is measured. Data available: Excel file Profile_salinity_temperature_velocity.xlsx contains along-slope velocity, temperature and salinity as a function of wall normal distance for slope angle 50 degrees, 65 degrees and 90 degrees respectively for the domain length 1.8 m.

  • Metadata record for data from ASAC Project 291 See the link below for public details on this project. From the abstracts of the referenced papers: Ground surveys of the ice sheet in Wilkes Land, Antarctica, have been made on oversnow traverses operating out of Casey. Data collected include surface elevation, accumulation rate, snow temperature, and physical surveys, the data are mostly restricted to line profiles. In some regions, aerial surveys of surface topology have been made over a grid network. Satellite imagery and remote sensing are two means of extrapolating the results from measurements along lines to an areal presentation. They are also the only source of data over large areas of the continent. Landsat images in the visible and near infra-red wavelengths clearly depict many of the large- and small-scale features of the surface. The intensity of the reflected radiation varies with the aspect and magnitude of the surface slope to reveal the surface topography. The multi-channel nature of the Landsat data are exploited to distinguish between different surface types through their different spectral signatures, e.g. bare ice, glaze, snow, etc. Additional information on surface type can be gained at a coarser scale from other satellite-borne sensors such as the ESMR, SMMR, etc. Textural enhancement of the Landsat images reveals the surface micro-relief. Features in the enhanced images are compared to ground-truth data from the traverse surveys to produce a classification of the surface types across the images and to determine the magnitude of the surface topography and micro-relief observed. The images can then be used to monitor changes over time. Landsat imagery of the Antarctic ice sheet and glaciers exhibit features that move with the ice and others that are fixed in space. Two images covering the same area but acquired at different times are compared to obtain the displacement of features. Where the time lapse is large, the displacement of obvious features can be scaled from photographic prints. When the two images are co-registered finer features and displacements can be resolved to give greater detail. Remote sensing techniques can be used to investigate the dynamics and surface characteristics of the Antarctic ice sheet and its outlet glaciers. This paper describes a methodology developed to map glacial movement velocities from LANDSAT MSS data, together with an assessment of the accuracy achieved. The velocities are derived by using digital image processing to register two temporally separated LANDSAT images of the Denman glacier and Shackleton Ice Shelf region. A derived image map is compared with existing maps of the region to substantiate the measured velocities. The velocity estimates from this study were found to correspond closely with ground-based measurements in the study area.

  • Motivation: One of the characteristics of this voyage is that we have long ice stations which last for a few days. Taking this opportunity, we decided to examine the diurnal change of snow properties at the fixed snow pit site. Since this measurement was not included in the original plan, Time interval was a bit variable from 3 hours to 5 hours depending on the progress of the other work. Observation items: Snow thickness, Temperature profile (every 3 cm), Grain size, Grain shape, Snow density, Hardness, Salinity Instruments: Folding scales, Spatula, Thermometer, Snow sampler, Magnifying glass, Salinometer Information pertaining to the dataset: Time - recorded in local time Hs - snow depth in cm Cloud measurements - oktas Water level - distance between snow surface and surface seawater in cm Depth - depth of the individual layer referenced to snow/ice interface (upper column) or snow surface (lower column) in cm Ta - air temperature in degrees celsius DH, FC, PP, DF, RG stand for Depth hoar, Faceted crystals, Precipitation particles, Decomposing and fragemented precipitation particles, Rounded grains - according to "The International Classification for Seasonal Snow on the Ground" (Colbeck et al., 1990). Weight - g Mid-depth - cm

  • AM03 borehole drilled December 2005. Consult Readme file for detail of data files and formats. 2011-2012 data may be final data from the unit owing to battery failure. The original project for this dataset was ASAC 1164, but recent data fall under the auspices of project AAS 4096.

  • This dataset contains routine measurements of snow and ice thickness, and snow-ice interface temperature, at 1m intervals along standard transects; snow property characterisation in snow pits measured at 0m, 50m and 100m along the transects; and sea ice cores acquired at various locations both along the transects and elsewhere on ice station floes during the 2012 SIPEX 2 marine science voyage. Ice temperature information is acquired from the cores, which are taken on-board for further analysis. The latter includes thin-section analysis of sea-ice stratigraphy and crystallography at -20C within the freezer lab on-board the ship. The cores are then cut up into 5cm sections and melted for analysis of salinity and stable oxygen isotopes. Observation items: Snow: - Thickness - Temperature profile (every 3 cm) - Snow-ice interface temperature at 1m intervals along the 100m transects - Grain size - Grain shape - Density - Hardness - Salinity - Stable oxygen isotope Ice: - Thickness - Freeboard - Draft - Temperature - Salinity - Stable oxygen isotope - Crystallography and texture - Density Instruments: Snow: Folding scales, Spatula, Thermometer, Snow sampler, Magnifying glass, Salinometer, Temperature and thickness probes, scales Ice: Drills, corers, ice-thickness tape measures, thermometer, salinometer, band-saw, cross-polarising filter, scales The data are recorded in log books (scanned copies are included in this dataset) and have been transferred into the standard AAD sea-ice database templates (in excel format) for each station.

  • AM06 borehole drilled January 2010. Profiling measurements conducted to test borehole diameter integrity.

  • AM04 borehole drilled January 2006. Profiling measurements conducted to test borehole diameter integrity.