Understanding the modes of the sea-ice thickness distribution: Processes and variability

海冰厚度分布（ITD）是了解北冰洋热量、质量和淡水收支的基础，在气候反馈中起着重要作用，对区域初级生产力、海上航行和海面作业具有很强的控制作用。根据多年生冰带（PIZ）观测估计的过渡段几乎总是在某些厚度（hm）上表现出一个突出的模态，大于与年冻结和最近打开的引线有关的模态厚度，并与之不同。这种模式被解释为未变形的多年冰处于其平衡厚度，或在热力学上向其平衡厚度增长。观测结果表明，在和平区内，温度的区域间、年际和年际变化显著，大约在1至5米的范围内。与脊冰的平均值、标准差和e折叠长度尺度等参数相比，过渡段的这一统计量受到的关注较少。该项目的结果将提高对冰厚这一生态和社会重要指标在空间和时间上变化的理解。PI假设冰的近模态厚度测量值相对于其他冰厚度测量值具有较小的偏差和随机误差，从而使模态成为过渡段的一个鲁棒参数。拟议研究的目标是提高对过渡段的认识，重点是模态hm，方法是改进对过渡段时空变化的估计，并加深对其在北极气候中的作用的了解。具体目标是(a)检验模型对观测误差具有鲁棒性的假设；(b)记录空气质素及过渡段其他参数在和平区的时空变化；(c)模拟过渡段和环流对规定强迫的变化，并将结果与观测结果进行比较；(d)研究模拟过渡段与脊状的公式和强迫资料误差的关系；(e)综合这些结果，作为对过渡段的一种新的分析和解释，强调过渡段及其变化。研究区域为1975-2010年的北冰洋PIZ。要考虑的时间尺度包括季节间、年际间和趋势，以及以小时或更长时间为单位的物理过程。

The sea-ice thickness distribution (ITD) is fundamental to understanding the heat, mass and freshwater budgets of the Arctic Ocean, plays important roles in climate feedbacks, and exerts strong control on regional primary productivity, marine navigation and surface operations. Estimates of ITD based on observations in the perennial ice zone (PIZ) nearly always exhibit a prominent mode at some thickness, hm, larger than and distinct from modal thicknesses associated with the annual freezeup and recently-opened leads. This mode has been interpreted as un-deformed multi-year ice at, or growing thermodynamically towards, its equilibrium thickness. Observations indicate significant inter-regional, annual and inter-annual variations of hm within the PIZ, over the approximate range 1 to 5 meters. This statistic of the ITD has received much less attention than other parameters, such as the mean, standard deviation and e-folding length scale of ridged ice. The results of this project will improve understanding of the variations in space and time of this ecologically and societally important measure of ice thickness.The PI hypothesizes that measurements of ice of near-modal thickness have reduced bias and random error with respect to other measures of ice thickness, thus making the mode a robust parameter of the ITD. The goal of the proposed research is to enhance understanding of the ITD, focusing on the mode hm, by producing improved estimates of space/ time variations of the ITD, and greater understanding of its role in Arctic climate. Specific objectives are (a) to test the hypothesis that the mode is robust to observational errors; (b) to document space and time variation of hm and other parameters of the ITD in the PIZ; (c) to simulate the variations of the ITD and hm as a response to prescribed forcing and compare results with observations; (d) to study the dependence of simulated ITDs on the formulation of ridging and on errors in the forcing data; and (e) to synthesize the results as a new analysis and interpretation of the ITD emphasizing hm and its variations. The study domain is the Arctic Ocean PIZ during the period 1975-2010. The timescales to be considered include inter-seasonal, inter-annual and trends, as well as physical processes acting on hours and longer.