Microstructure of First Year Sea Ice Ridges

• Main Authors: Johnston, Michelle, Barker, Anne
• Format: Report
• Language: unknown
• Published: National Research Council Canada 2000
• Subjects: Newfoundland; Sea ice
• Online Access: https://dx.doi.org/10.4224/12340979; https://nrc-publications.canada.ca/eng/view/object/?id=458d2a71-fedf-4741-af2b-c0134f0c6fe7

First year sea ice ridges were characterized off the West Coast of Newfoundland from 07 to 22 March 1999. This report presents a comprehensive investigation of five ridges sampled during the March 1999 program. The ice microstructure of the ridges is correlated to the bulk physical properties (temperature, salinity and density) and consolidated layer thickness of the ridged ice. The ridges had a maximum sail height that ranged from 1.5 to 3.8 m. The consolidated layer thickness of the ridged ice ranged from 0.7 to 2.1 m and the total ice thickness varied from 1.8 to 5.0 m. The temperature of the ice cores was just below 0°C. The average bulk ice salinity ranged from 3.6 to 4.1 ‰, with a maximum of 6 ‰. Ice densities from the examined ridge site ranged from 0.85 to 0.93 Mg/m³. The warm temperatures, high porosity and low density of the ice indicated temperate ridges in a deteriorated state. Due to the deteriorated state of the ridged ice, it is expected that the measured average salinity of the ridges may have decreased after the ridge formed. The sail blocks showed that the ice involved in the ridge formation consisted of columnar grained ice, predominantly. Examination of the macrostructure of ridged ice cores showed highly porous, loosely consolidated ice with discrete banding. The microstructure of the cores revealed a non-uniform matrix comprised of mostly granular ice, with some coarse frazil particles and elongated columns.