Trends in the Dates of Ice Freeze-up and Breakup over Hudson Bay, Canada

• Published in: ARCTIC
• Main Authors: Gagnon, Alexandre S., Gough, William A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Arctic Institute of North America 2010
• Subjects: breakup; climate change; freeze-up; Hudson Bay; sea ice; temperature; Baie d’Hudson; changements climatiques; déglacement; formation; glace marine; Canada; Hudson; Kendall; Baie James; Arctic; Sea ice; James Bay
• Online Access: https://journalhosting.ucalgary.ca/index.php/arctic/article/view/63512

Hudson Bay experiences a complete cryogenic cycle each year. Sea ice begins to form in late October, and the Bay is usually ice-free in early August. This seasonally varying ice cover plays an important role in the regional climate. To identify secular trends in the cryogenic cycle, we examined variability in the timing of sea-ice formation and retreat during the period 1971– 2003. The dates of ice freeze-up and breakup at 36 locations across Hudson Bay were catalogued for each year from weekly ice charts provided by the Canadian Ice Service. We used the nonparametric Mann-Kendall test to determine the statistical significance of the trends and the Theil-Sen approach to estimate their magnitude. Our results indicate statistically significant trends toward earlier breakup in James Bay, along the southern shore of Hudson Bay, and in the western half of Hudson Bay, and toward later freeze-up in the northern and northeastern regions of Hudson Bay. These trends in the annual ice cycle of Hudson Bay coincide with both the regional temperature record and the projections from general circulation models. If this trend toward a longer ice-free season continues, Hudson Bay will soon face important environmental challenges. Chaque année, la Baie d’Hudson connaît un cycle cryogénique complet. La formation de la glace marine commence en fin d’octobre et la baie est habituellement exempte de glace en début d’août. La présence saisonnière du couvert de la glace de la Baie d’Hudson revêt une importance primordiale sur le climat régional. Dans cet article, on étudie la variabilité des dates de formation et de retrait de la glace marine de la Baie d’Hudson dans le but d’identifier des tendances séculaires durant la période 1971 à 2003. Les dates de formation et de retrait de la glace marine ont été cataloguées pour tous les ans dans le cas de 36 endroits à travers la Baie d’Hudson et la Baie James en utilisant des images hebdomadaires publiées par le Service canadien des glaces. Le test non paramétrique Mann Kendall a été ...