The 2017 Reversal of the Beaufort Gyre: Can Dynamic Thickening of a Seasonal Ice Cover During a Reversal Limit Summer Ice Melt in the Beaufort Sea?
The 2017 Reversal of the Beaufort Gyre: Can Dynamic Thickening of a Seasonal Ice Cover During a Reversal Limit Summer Ice Melt in the Beaufort Sea?
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DOI：
10.1029/2020jc016796
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发表时间：
2020-12-01
影响因子：
3.6
通讯作者：
Galley, R. J.
中科院分区：
文献类型：
--
作者：
Babb, D. G.;Landy, J. C.;Galley, R. J.
2017年冬季，半永久性博福特高压崩溃，反气旋性博福特环流逆转。这一逆转促使冰向东运动穿过北极西部，导致海冰向班克斯岛汇聚，并阻止了多年海冰通过环流的循环，阻止了博福特海的补充。在逆转之前，博福特在2016年9月的无冰条件下形成了非常薄的季节性冰盖。随着2017年1月逆转的开始，辐合在冬季驱动了不典型的动力增厚。到3月底，尽管季节性冰占冰盖的97%，但逆转创造了CryoSat-2记录中最厚，最粗糙和最大的区域冰盖。在博福特海，以前的工作表明，冬季冰输出可以为该地区增加夏季冰融化的先决条件，但在2013年4月的短暂逆转有助于减少夏季冰损失。因此，预计2017年冬季末的变形冰盖将限制夏季融化。尽管如此，博福特冰盖下降到9月第四低的地区，因为环流在4月重新建立，分散的冰漂移打破了包，否定了逆转的早期预处理。我们的工作强调，动态冬季增厚的区域海冰覆盖，例如在环流逆转，提供了限制夏季冰损失的潜力，但在春季的动态强迫决定了这种调节是否进行到融化季节。
During winter 2017, the semipermanent Beaufort High collapsed and the anticyclonic Beaufort Gyre reversed. The reversal drove eastward ice motion through the Western Arctic, causing sea ice to converge against Banks Island, and halted the circulation of multiyear sea ice via the gyre, preventing its replenishment in the Beaufort Sea. Prior to the reversal, an anomalously thin seasonal ice cover had formed in the Beaufort following ice-free conditions during September 2016. With the onset of the reversal in January 2017, convergence drove uncharacteristic dynamic thickening during winter. By the end of March, despite seasonal ice comprising 97% of the ice cover, the reversal created the thickest, roughest, and most voluminous regional ice cover of the CryoSat-2 record. Within the Beaufort Sea, previous work has shown that winter ice export can precondition the region for increased summer ice melt, but that a short reversal during April 2013 contributed to a reduction in summer ice loss. Hence, the deformed ice cover at the end of winter 2017 could be expected to limit summer melt. In spite of this, the Beaufort ice cover fell to its fourth lowest September area as the gyre re-established during April and divergent ice drift broke up the pack, negating the reversal's earlier preconditioning. Our work highlights that dynamic winter thickening of a regional sea ice cover, for instance during a gyre reversal, offers the potential to limit summer ice loss, but that dynamic forcing during spring dictates whether this conditioning carries through to the melt season.