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Field instruments

by Vincent Favier - 12 October 2016 ( maj : 9 November 2016 )

The traverse instruments

The raid brings on board many instruments. Besides the core drill, the team will have a radar to track isochronous snow layers, a Laserscan, laser system used for measuring surface irregularities, weather stations, and a range of tools associated with snow physical properties ... More precisely, tools and their main referents are:

  • Felics, mini-Felics - Vincent Favier
  • Forposssum - Laurent Arnaud
  • Radar + CMP - Emmanuel Le Meur
  • POSSSUM, ASSSAP, Snow-micro-pen - Ghislain Picard / Laurent Arnaud
  • Laserscan OSUG - Vincent Favier
  • RLS - Ghislain Picard
  • Station météo - Vincent Favier
  • Multiphoto - Laurent Arnaud
  • differential GPS - Emmanuel Le Meur
  • mini rover - Laurent Arnaud

Instruments functions

  • POSSSUM and ASSSAP are instruments to measure the size of snow grains in borehole in snow. POSSSUM is the biggest and most heavy, it can be used up to 20 m depth. ASSSAP is a lightweight version and is very efficient for shallow measurements up to 1m. Internally they use a small laser operating in the infrared (1.3 microns wavelength) and measure the beam reflected by the snow. The grain size is deduces because the reflectance of snow in the infrared (1.3 microns) is very sensitive to the size of snow grain.

Arnaud, L., G. Picard, N. Champollion, F. Domine, JC. Gallet, E. Lefebvre, M. Fily and JM. Barnola. Measurement of vertical profiles of snow specific surface area with a one centimeter resolution using infrared reflectance: Instrument description and validation. Journal of Glaciology, 57(201), 17-29, 2011 TOC

Q. Libois, Picard, G., Arnaud, L., Dumont, M., Lafaysse, M., Morin, S., and Lefebvre, E., Summertime evolution of snow specific surface area close to the surface on the Antarctic Plateau, The Cryosphere, 9, 2383-2398, doi:10.5194/tc-9-2383-2015, 2015

  • The snow micropen (SMP) measures the mechanical properties of the snow at very high resolution. It is made of a small conical tips fitted with a force sensor. The tips is slowly inserted into the snow up to 2 m depth, and the force is measured every 4 microns! The profile of force provides indirect information on the snow microstructure. Because this instruments is fast and nearly non-distructive for the snow, we primarily use it to estimate the spatial variability of snow.
  • Rugged Laserscan (RLS): This instrument measures the elevation of the surface at very high resolution providing a map of the surface roughness. RLS was developed in our lab because we needed a very robust system able to run every day in Antarctica even in winter by -80°C. No commercial laserscan is able to achieve these performances. RLS has been operating at Dome C since 2015 and in the Alps in the most windy areas. We bring an RLS instrument on the traverse in complement of the OSUG Laserscan to increase the chance to collect elevation data. This is so important for this project that we prefer a multi-fold strategy!

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