Abstract:
Sea ice is a multiphase material comprised of a pure ice matrix containing liquid brine, solid salts, microalgae, gases and other impurities which exist together in inclusions and pores within the matrix. Pure ice crystals are comprised of a tight, hydrogen bound, hexagonal network of dipolar H2O molecules formed by the relatively strong covalent bonding of the hydrogen and oxygen atoms. The strength of the hydrogen bonds increase as the distance between the water molecules reduce due to lower thermal motions in a cooling environment. Sodium chloride ions that are highly soluble in water, are insoluble in ice with the result that brine is rejected or displaced by the ice during the formation of sea ice systems such as pancake and pack ice elements. This brine either (i. drains out of the ice matrix through channels, or (ii. it remains trapped in pockets between pure ice crystals, depending of the permeability of the matrix. The characteristics of sea ice are typically most dependant on temperature, bulk salinity and liquid brine content parameters. These parameters are all closely related and, in idealised gas-free ice, any two can be used to calculate the third [Hunke et al, 2011]. Temperature and bulk salinity values can most easily be directly measured from in-situ ice samples. The presentation will focus on the testing and analysis of pancake ice samples collected at two single locations on the outer and inner edges of the Antarctic marginal ice zone (MIZ. during research cruises in the winters of 2017 and 2018. We shall show how the parameters vary with their distance from the open sea at the outer edge of the MIZ. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.
