Frontal Circulation and Submesoscale Variability during the Formation of a Southern Ocean Mesoscale Eddy
Frontal Circulation and Submesoscale Variability during the Formation of a Southern Ocean Mesoscale Eddy
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DOI：
10.1175/jpo-d-16-0266.1
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发表时间：
2017-07-01
影响因子：
3.5
通讯作者：
Stamper, Megan
中科院分区：
文献类型：
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作者：
Adams, Katherine A.;Hosegood, Philip;Stamper, Megan
2015年5月，在中尺度下表面混合层演变研究巡航期间，在斯科舍海进行的观测捕获了中尺度下，O（1-10）km，沿着中尺度O（10-100）km弯曲边缘的变率，正好在它与南极绕极流分离并形成气旋涡流时;直径为120 km。曲流发展于斯科舍海，德雷克海峡以东的一个漩涡丰富的地区，在那里亚南极和极锋汇聚，并发生亚南极模式水（SAMW）的修改。现场测量结果显示，丰富的亚中尺度结构的温度和盐度和损失的锋面完整性沿着新形成的南部部门的涡流。一个数学框架，估计垂直速度从配置漂流和水平水速度的时间序列，在一定的简化假设适合当前的数据集。在北方（南方）涡区发现O（100）mday（1）的上升流（下降流）速率。亚中尺度不稳定性的有利条件被发现在混合层，特别是在密度锋附近的调查开始。较浅的混合层深度和增加分层是在稍后的调查中观察到的前缘的内边缘。温度-盐度（T-S）空间的演变表明，在2天以上的200米以上的水团性质的修改。沿着sigma（theta）-27-27.2 kgm（-3）的变化对斯科舍海在比以前观测到的更精细的时空尺度上的模态和中层水转化具有与气候相关的影响。
Observations made in the Scotia Sea during the May 2015 Surface Mixed Layer Evolution at Submesoscales (SMILES) research cruise captured submesoscale, O(1-10) km, variability along the periphery of a mesoscale O(10-100) km meander precisely as it separated from the Antarctic Circumpolar Current (ACC) and formed a cyclonic eddy; 120 km in diameter. The meander developed in the Scotia Sea, an eddy-rich region east of the Drake Passage where the Subantarctic and Polar Fronts converge and modifications of Subantarctic Mode Water (SAMW) occur. In situ measurements reveal a rich submesoscale structure of temperature and salinity and a loss of frontal integrity along the newly formed southern sector of the eddy. A mathematical framework is developed to estimate vertical velocity from collocated drifter and horizontal water velocity time series, under certain simplifying assumptions appropriate for the current dataset. Upwelling (downwelling) rates of O(100) mday (1) are found in the northern (southern) eddy sector. Favorable conditions for submesoscale instabilities are found in the mixed layer, particularly at the beginning of the survey in the vicinity of density fronts. Shallower mixed layer depths and increased stratification are observed later in the survey on the inner edge of the front. Evolution in temperature-salinity (T-S) space indicates modification of water mass properties in the upper 200m over 2 days. Modifications along sigma(theta) - 27-27.2 kgm(-3) have climate-related implications for mode and intermediate water transformation in the Scotia Sea on finer spatiotemporal scales than observed previously.