Tom Carrieres

A case Study of old-ice import and export through Peary and Sverdrup Channels in the Canadian Arctic Archipelago: 1998–2005

Abstract This case Study attempts to quantify the amount and timing of the import, export and through-flow of old ice in the Peary Channel–sverdrup Channel area of the northern Canadian Arctic Archipelago during the period 1998–2005. The Study combines quantitative weekly area-averaged ice coverage evaluations from the Canadian Ice Service (CIS) Digital Archive with detailed analysis of Radarsat imagery and ice-motion results from the CIS ice-motion algorithm. The results Show that in 1998 more than 70% of the old ice in Peary–sverdrup was lost, half by melt and export to the South and the other half by export north into the Arctic Ocean, and that no Arctic Ocean old ice was imported into Peary–sverdrup. A net import of 10% old ice was Seen in 1999, with Some indication of through-flow into Southern channels. In 2000, no net import of old ice occurred in Peary–sverdrup, but there was Significant through-flow, with evidence of old ice reaching the Northwest Passage by November. Full recovery of the old-ice regime was complete by the end of 2001. More than two-thirds of the recovery was due to the in Situ formation of Second-year ice. Conditions in the following 3 years were near normal.

Bergy bit and growler melt deterioration

The Canadian Ice Service, Environment Canada, is currently developing an operational iceberg forecasting model; the present work forms part of that effort. While existing models predict iceberg drift and deterioration, the new model will account for calving that produces smaller ice pieces and subsequently track the drift and melt of the calved pieces. Bergy bits and growlers, which we consider here to be ice pieces in the size range from 3 to 20 m, can cause large forces upon impact with offshore structures. The probability of encountering these bergy bits and growlers is of significant interest to marine transportation and offshore resource development. Calving due to wave-induced erosion at the waterline of a floating iceberg can produce many thousands of small ice pieces having a wide distribution of sizes. These small ice pieces then melt as individual entities and eventually disappear. Since the calving events occur periodically, there is a continual supply of small ice pieces in the neighborhood of the parent iceberg. The focus of the present paper is on the evolution of the size-frequency distribution function for the calved ice pieces. It makes use of the initial distribution function following the calving event discussed by Savage et al. (2000). Dimensional analysis, laboratory tests, and field observations are applied to obtain simple correlations and devise a melt law for the smaller ice pieces. This melt law is then used to determine the temporal evolution of the small ice piece size-frequency distribution function.