| Résumé | This report is the second of a two-year study that examines means by which to incorporate level, landfast first-year ice in the sub-Arctic into the Ice Strength Charts that are issued by the Canadian Ice Service during the summer months. It is suggested that, if sub-Arctic ice is to be included in future Ice Strength Charts, the contour lines of equal strength in the Charts should be based upon the calculated flexural strength of the ice. The most accurate approach for that calculation requires ice property measurements, which are not usually available. Alternately, a second approach was explored: data output from the thermodynamic model used by the Canadian Ice Service was used to calculate the flexural strength of the ice. Preliminary analysis showed that the air temperatures, snow and ice thickness, and ice temperatures forecast from the model were in reasonably good agreement with measurements made on first-year ice in the high Arctic and the sub-Arctic. It was suggested that output from the thermodynamic model could be used to calculate the flexural strength of first-year ice in the sub-Arctic until about mid-May, when the ice had about 35% of its maximum mid-winter strength. In the high Arctic, where the ice decay process is less complex, the forecasted data could be used to calculate the ice strength until early July, when the ice had about 10 to 15% of its maximum mid-winter strength. |
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