Properties of Level Landfast Ice and Hummocked Ice near Nain, Labrador

This report discusses property measurements that were made on level first-year sea ice near Nain, from early February to mid May 2004. Ice thickness ranged from 0.41 to 0.65 m in February, and 0.89 to 1.20 m in mid-May. The highest borehole strengths were measured in March, when the ice was coldest. Results showed that, in general, ice strength decreased more rapidly towards the top and bottom surfaces than in the ice interior. The strength reduction was due to ice decay, clear evidence of which was provided by the deteriorated state of the extracted cores, and changes in the temperature and salinity of the ice. Measurements are also given for hummocked ice sites that were sampled in a quasi-stable area of landfast ice, in April. The ice surface relief increased, as did the ice and snow thickness, as the hummock field was penetrated. Ice thickness at the first site ranged from 0.99 to 1.17 m, whereas ice at the fourth site ranged from 1.14 to 2.20 m thick. The hummocked ice was isothermal at near melting temperatures throughout its full thickness. The ice salinity was minimal in the top ice, ranged from 4 to 5\ufffd in the ice interior, and was upwards of 8\ufffd towards the bottom ice. The highest borehole strength was measured in the interior of the ice. On average, the hummocked was thicker and stronger than the level landfast ice (for the same time of year).NRC publication: Ye