Morphology and 2D spatial strength distribution in two Arctic first-year sea ice ridges

Abstract Geometry and morphology of two first-year sea ice ridges, one in the North-western Barents Sea in 2005 and one in the Arctic Ocean in 2006, were examined. Altogether 130 freeze bonding contacts between the ice blocks in the ridge sail were examined; and the average freeze bond length and width were 0.28 m and 0.14 m, respectively; the average length/width ratio was 2.2 (2005) and 1.8 (2006). The average freeze bond length to average block length ratio was 0.33 (2005) and 0.35 (2006). Furthermore the uniaxial compression tests were conducted in the field on the first-year sea ice. The temperature, salinity and density were measured for each ice sample and the brine and air volume was calculated. Both vertical and horizontal ice samples were tested. The ratio between vertical and horizontal strength was 2.0 for the level ice and 1.1 both for the consolidated layer and for the unconsolidated part of the ice ridge. Weak zones were discovered in the ice ridges, and the ice strength varied by a factor of more than 3 along both vertical and horizontal directions. The strength variation for the vertical samples within different parts of an ice ridge was at the same level: 50–55% for the 2005 feature and around 40% for the 2006 ridge. The corresponding strength variation for the level ice (2006) was estimated as 42.2% for the vertical samples and 25.2% for the horizontal ones.