Decay-Induced Changes in the Physical and Mechanical Properties of First Year Ice.

• Main Authors: Johnston, Michelle, Frederking, Robert, Timco, Garry
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2001
• Subjects: Arctic; Sea ice
• Online Access: https://nrc-publications.canada.ca/eng/view/accepted/?id=e78bd0fa-7f5d-487b-a89b-9d4755e5aab7; https://nrc-publications.canada.ca/eng/view/object/?id=e78bd0fa-7f5d-487b-a89b-9d4755e5aab7; https://nrc-publications.canada.ca/fra/voir/objet/?id=e78bd0fa-7f5d-487b-a89b-9d4755e5aab7

This paper describes the results and analysis 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 during which time the mean air temperature steadily increased from –15°C to a maximum of +7.5°C. The ice was 1.20 m thick when the program began on 21 May and had decreased to 0.83 m thick by 19 July. On average, the ice ablated at a rate of about 23 mm/day during the program. Initially, the average salinity throughout the full thickness of ice was 5.5 ‰. By 19 July measurements showed that the bulk salinity of the ice had decreased to less than 0.5 ‰. The upper and lower surfaces of the ice began to desalinate before the bulk layer of ice. One of the main components of the study was to measure the in situ confined compressive strength of the ice with a borehole jack assembly; 110 borehole jack tests were conducted from 21 May to 19 July. Over the nine-week period, the in situ strength of the ice decreased from 12 to 3 MPa. Measurements showed that the ice maintained a strength of 3 MPa during the last three weeks of the study. The ice continued to ablate during that time. Most of the decrease in ice strength resulted from changes in the physical properties of the ice. NRC publication: Yes