East-west asymmetry in long-term trends of landfast ice thickness in the Hudson Bay region, Canada
East-west asymmetry in long-term trends of landfast ice thickness in the Hudson Bay region, Canada
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加拿大哈德逊湾地区固定冰厚度长期趋势的东西不对称
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
W. Gough
中科院分区：
文献类型：
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作者：
A. Gagnon;W. Gough
哈德逊湾地区（HBR）的冰盖每年都会经历一个完整的低温循环。通常在10月和11月结冰，冰盖厚度在3月下旬至5月达到峰值，HBR水体通常从8月初开始无冰。在这项研究中，根据加拿大冰局编制的每周冰观测，确定了每年冰厚度年度峰值的时间和幅度。使用Mann-Kendall检验来确定时间趋势的统计显著性，并使用Theil-Sen方法估计其幅度。结果表明，陆地固结冰厚度的时间变化趋势不对称；在哈德逊湾的西侧，随着时间的推移，冰盖的厚度在统计上显著增加，而在东侧，冰盖的厚度略有减少，但没有统计学意义。这种不对称性与气温、积雪深度以及冰冻结和破裂日期的变化有关。许多站点的最大冰厚增加与秋季气温负趋势导致的早期冻结密切相关。然而，最大冰厚的变化与覆盖地面的雪量的变化呈反比。这些结果与一般环流模式（GCMs）的预估以及在北极其他地区观测到的海冰范围和厚度的减少形成对比。这一矛盾必须在区域气候变化影响评估中加以解决。
Ice cover in the Hudson Bay region (HBR) goes through a complete cryogenic cycle each year. Freeze-up typically occurs in October and November, ice cover reaches its peak thickness from late March to May, and water bodies in the HBR are usually ice-free beginning in early August. In this study, the timing and magnitude of the annual peak in ice thickness were identified for each year from weekly ice observations compiled by the Canadian Ice Service. The Mann-Kendall test was used to determine the statistical significance of the temporal trends, and their magnitude was esti- mated using the Theil-Sen approach. The results indicate an asymmetry in temporal trends of land- fast ice thickness; statistically significant thickening of the ice cover over time was detected on the western side of Hudson Bay, while a slight thinning lacking statistical significance was observed on the eastern side. This asymmetry is related to the variability of air temperature, snow depth, and the dates of ice freeze-up and break-up. Increasing maximum ice thickness at a number of stations is cor- related to earlier freeze-up due to negative temperature trends in autumn. Nevertheless, changes in maximum ice thickness were reciprocal to the variability in the amount of snow covering the ground. These results are in contrast to the projections from general circulation models (GCMs), and to the reduction in sea-ice extent and thickness observed in other regions of the Arctic. This contradiction must be addressed in regional climate change impact assessments.