Decay of First-Year Sea Ice

• Main Authors: Johnston, Michelle, Frederking, Robert, Timco, Garry
• Format: Report
• Language: unknown
• Published: National Research Council Canada 2001
• Subjects: Arctic; Sea ice
• Online Access: https://dx.doi.org/10.4224/12326980; https://nrc-publications.canada.ca/eng/view/object/?id=1acfa2a7-7e2b-416c-b432-9ef714717465

This report describes analysis results of one season of measurements of decayed first year sea ice in the central Canadian Arctic. The study was conducted from 21 May to 19 July 2000. Mean air temperatures steadily increased from �15�C to a maximum of +7.5�C. The ice was 1.20 m thick on 21 May and had ablated to 0.83 m by 19 July. Ice ablation occurred at a rate of about 23 mm/day. The initial bulk ice salinity of 5.5 � had decreased to less than 0.5 � by 19 July. The upper and lower surfaces of the ice began to desalinate before the bulk layer of ice. The confined compressive strength of the ice was measured in 110 borehole jack tests. All strength profiles showed that the in situ ice strength decreased as the decay season progressed. Over the nine-week period, the average full-thickness in situ strength of the ice decreased from 12 MPa to 3 MPa. Most of the decrease in in situ ice strength resulted from changes in the physical properties of the ice. During the last three weeks of the study, the ice maintained a strength of 3 MPa whereas ice ablation continued until the end of the study.