Brazil Current surface circulation and energetics observed from drifting buoys
Brazil Current surface circulation and energetics observed from drifting buoys
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DOI：
10.1029/2008jc004900
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发表时间：
2009-10
影响因子：
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通讯作者：
L. R. Oliveira;A. Piola;M. Mata;I. Soares
中科院分区：
文献类型：
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作者：
L. R. Oliveira;A. Piola;M. Mata;I. Soares
[1] 通过分析 13 年的表面漂流数据（存储在 0.5° × 0.5° 网格上），研究了西南大西洋平均表面环流、其相关的变异性和能量学。特别关注该域的以下三个主要区域特征：巴西海流、马尔维纳斯海流和巴西-马尔维纳斯交汇处。对于西边界流，平均场显示速度大于 45 cm s−1，与高水平的变异性相关（标准偏差超过 15 cm s−1），而标准偏差的最高值出现在巴西-马尔维纳斯汇合处（>25 cm s−1）。相反，在大多数域中，发现的平均速度 (20–30 cm s−1) 和相关标准偏差 (<15 cm s−1) 通常较低。在西边界流及其延伸区中估计每单位质量平均流量的动能较高值（265-1000 cm2 s−2）。除沿巴西洋流路径的某些区域外，沿西边界流主喷流的涡动能普遍低于平均流的动能。相比之下，巴西-马尔维纳斯交汇处显示的涡流动能水平与平均动能相当或更大（∼2500 cm2 s−2）。远离边界，表面环流的大部分动能都在涡流场中。此外，对动能转换项的分析表明，巴西洋流沿线存在正压不稳定性。在巴西海流核心的大部分地区，动能转换术语指的是从平均动能到涡流动能。
[1] The southwestern Atlantic mean surface circulation, its associated variability and energetics are studied through the analysis of 13 years of surface drifter data binned onto a 0.5° × 0.5° grid. Special attention is given to the following three main regional features of the domain: the Brazil Current, the Malvinas Current, and the Brazil-Malvinas Confluence. For the western boundary currents, the mean field reveals velocities larger than 45 cm s−1, associated with high levels of variability (standard deviation of more than 15 cm s−1), while the highest values of standard deviation are found in the Brazil-Malvinas Confluence (>25 cm s−1). Conversely, over most of the domain the mean velocities found (20–30 cm s−1) and associated standard deviations (<15 cm s−1) are generally lower. High values of kinetic energy of the mean flow per unit mass (265–1000 cm2 s−2) are estimated in the western boundary currents and their extensions. Eddy kinetic energy along the main jet of the western boundary currents is generally lower than the kinetic energy of the mean flow, except for some areas along the Brazil Current path. In contrast, the Brazil-Malvinas Confluence reveals eddy kinetic energy levels comparable or larger (∼2500 cm2 s−2) than the mean kinetic energy. Away from the boundary, most of the kinetic energy of the surface circulation is in the eddy field. Furthermore, the analysis of the kinetic energy conversion term suggests the presence of barotropic instabilities along the Brazil Current. Over most of the Brazil Current core, the kinetic energy conversion term points from the mean to eddy kinetic energy.