The goal of the present project is to utilize modern technology and interdisciplinary work to close a fundamental gap in the description of the medium sea ice. We will for the first time apply synchrotron-based X-ray computed micro-tomography (XMT) to obt ain a three-dimensional description of the sea-ice-matrix.
XMT has earlier been successfully applied to the three-dimensional monitoring of snow, polar firn, and artificial ice samples. The synchrotron-based approach allows for a resolution of a few mik rometers, necessary to describe the sea ice microstructure properly.
Size distribution functions and the detailed morphology of ice, liquid and gas inclusions will be determined, to improve the understanding of the dynamic freezing process of sea ice and the formation of permeable pore networks.
Brine pocket migration is one important mechanism during morphological metamorphosis of brine pocket networks. Intermittent phase transitions during warming and cooling, leading to pore widening/coarsening and reshaping, is another important process. A temperature-gradient setup with XMT will be used to monitor the dynamics near the sea ice seawater interface, and the migration of brine pockets. In combination with thermal cycling experiments this will improve microphysical modelling of natural sea ice.
Disregarding a few reported observations of salt crystals obtained by optical means, there is a lack in observations
of the locations of impurities in sea ice, necessary to develop fractionation theories. X-Ra y based
micro-spectroscopy at the LUCIA beamline of the Swiss Light Source (SLS) allows to study the chemical
composition (chemical environment (NEAXFS) and the ordering (EXAFS)) of inclusions. First tests of sea ice micro-spectroscopy are planned.
The present approach will contribute to basic resarch on the microscopic scale. It will also help to solve
macroscopic scientific problems related to the medium sea ice in polar regions.