Variability of the Antarctic slope current system in the northwestern Weddell Sea
Variability of the Antarctic slope current system in the northwestern Weddell Sea
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DOI：
10.1175/jpo-d-17-0030.1
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发表时间：
2017-12
影响因子：
3.5
通讯作者：
M. Azaneu;K. Heywood;B. Queste;A. Thompson
中科院分区：
文献类型：
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作者：
M. Azaneu;K. Heywood;B. Queste;A. Thompson
从南极大陆架流出的密集水与南极坡锋的强度和位置密切相关。本研究利用2012年部署的三个海洋滑翔机的高时间和空间分辨率测量数据，探讨了南极坡锋系统的短期和空间变异性以及调节跨坡交换的机制。沿着南极半岛东部和南奥克尼群岛西部的22个部分按区域分组，并由等深线组成。鲍威尔盆地周围的锋面位置是一致的，主要在500米和800米等深线之间变化。在大部分研究区，流动是底部强化的。南极斜坡流（1000米以上）的沿坡输送在0.2和5.9 Sv （1 Sv≡10^6 m^3 s^(−1)）之间变化，不表现出区域格局。速度场的大小显示出很大的变化，可达其平均值的两倍。在有稠密水的区域观察到较高的涡流动能（0.003 m^2 s^(−2)），可能是因为底层斜压不稳定。位涡量沿等线向陆架方向和密集水层方向分布呈增加趋势。位于南奥克尼群岛以西的滑翔机部分表明与威德尔锋有关的气流向北，这与之前对平均环流的估计不同。这项研究提供了一些与活跃涡场相关的高频变异性的首次观测证实，这是最近在该地区的数值模拟所提出的。
The dense water outflow from the Antarctic continental shelf is closely associated with the strength and position of the Antarctic Slope Front. This study explores the short-term and spatial variability of the Antarctic Slope Front system and the mechanisms that regulate cross-slope exchange using highly temporally and spatially resolved measurements from three ocean gliders deployed in 2012. The 22 sections along the eastern Antarctic Peninsula and west of the South Orkney Islands are grouped regionally and composited by isobaths. There is consistency in the front position around the Powell Basin, varying mostly between the 500- and 800-m isobaths. In most of the study area the flow is bottom intensified. The along-slope transport of the Antarctic Slope Current (upper 1000 m) varies between 0.2 and 5.9 Sv (1 Sv ≡ 10^6 m^3 s^(−1)) and does not exhibit a regional pattern. The magnitude of the velocity field shows substantial variability, up to twice its mean value. Higher eddy kinetic energy (0.003 m^2 s^(−2)) is observed in sections with dense water, possibly because of baroclinic instabilities in the bottom layer. Distributions of potential vorticity show an increase toward the shelf along isopycnals and also in the dense water layer. Glider sections located west of the South Orkney Islands indicate a northward direction of the flow associated with the Weddell Front, which differs from previous estimates of the mean circulation. This study provides some of the first observational confirmation of the high-frequency variability associated with an active eddy field that has been suggested by recent numerical simulations in this region.