Seasonal evolution of the sea-ice floe size distribution in the Beaufort and Chukchi seas
Seasonal evolution of the sea-ice floe size distribution in the Beaufort and Chukchi seas
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DOI：
10.1525/elementa.305
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发表时间：
2018-07
期刊：
影响因子：
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通讯作者：
H. Stern;A. Schweiger;M. Stark;Jinlun Zhang;M. Steele;B. Hwang
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文献类型：
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作者：
H. Stern;A. Schweiger;M. Stark;Jinlun Zhang;M. Steele;B. Hwang
极地海域浮冰的大小分布影响着冰盖的动力学和热力学，冰-海模型开始在模拟中包括浮冰大小分布（FSD）。FSD以前曾被报道遵循x −α形式的幂律，其中x是絮凝物的大小，-α表征絮凝物的数量随着x的增加而急剧减少。不同的研究发现了不同的α值和不同的x范围，幂律适用于这些范围。我们发现，幂律描述了FSD在博福特和楚科奇海合理地超过浮冰大小从2到30公里，基于187可见光波段卫星图像（分辨率250米）在春季到秋季的2013年和2014年。平均幂律指数经历一个季节性周期，其中α在春季增加，在7月或8月达到峰值，在秋季下降。六月是春季消防处向夏季消防处过渡的月份。这个周期是一致的过程中，浮冰分解在春季，其次是优先融化较小的浮冰在夏季和返回较大的浮冰后，秋季冻结。我们还分析了12个高分辨率的卫星图像附近的低分辨率图像在空间和时间。我们发现，从高分辨率图像的FSD遵循幂律的浮冰大小从10米到3公里。虽然相应的高分辨率和低分辨率图像的幂律指数在严格的统计意义上并不总是匹配的，但它们表明FSD在宽范围的絮凝物尺寸上遵循单一幂律的可能性。这项研究涵盖了更大的空间和时间采样空间，是基于更多的卫星图像比以往的研究。结果已被用于模型校准和验证。
The size distribution of ice floes in the polar seas affects the dynamics and thermodynamics of the ice cover, and ice-ocean models are beginning to include the floe size distribution (FSD) in their simulations. The FSD has previously been reported to follow a power law of the form x −α, where x is the floe size and –α characterizes how steeply the number of floes decreases as x increases. Different studies have found different values of α and different ranges of x over which the power law applies. We found that a power law describes the FSD in the Beaufort and Chukchi seas reasonably well over floe sizes from 2 to 30 km, based on 187 visible-band satellite images (resolution 250 m) acquired during spring through fall of 2013 and 2014. The mean power-law exponent goes through a seasonal cycle in which α increases in spring, peaks in July or August, and decreases in fall. June is the transition month from spring FSD to summer FSD. This cycle is consistent with the processes of floe break-up in spring followed by preferential melting of smaller floes in summer and the return of larger floes after fall freeze-up. We also analyzed 12 high-resolution satellite images acquired near the low-resolution images in space and time. We found that the FSDs from the high-resolution images follow power laws over floe sizes from 10 m to 3 km. While the power-law exponents of the corresponding high- and low-resolution images do not always match in a strict statistical sense, they suggest the plausibility that the FSD follows a single power law over a wide range of floe sizes. This study covers a larger spatial and temporal sampling space and is based on more satellite images than previous studies. Results have been used for model calibration and validation.