A Zonal Pathway for NADW in the South Atlantic
A Zonal Pathway for NADW in the South Atlantic
复制标题
南大西洋 NADW 的区域路径
DOI：
10.1007/s10872-005-0058-7
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发表时间：
2005
影响因子：
2.3
通讯作者：
A. Thurnherr
中科院分区：
文献类型：
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作者：
N. Hogg;A. Thurnherr
20世纪90年代，在南极中层（AAIW）、北大西洋深水（NADW）和南大西洋的南极底层水（AABW）内进行了几次大规模的中性浮力浮子部署，一些水文部分也被占用。在这里，我们使用的空间和时间的平均速度测量这些浮子，结合水文剖面数据和各种估计的区域电流传输从停泊的电流计阵列，以确定三个主要的亚温跃层水团在纬19 ° S和30 ° S之间的南大西洋的带状带的环流。我们集中在这一地区，因为历史文献表明，这是深西部边界电流包含NADW分叉。为了支持这一概念，我们发现，一个净约5希沃特。15 - 20西弗的15 - 20西弗穿过19 ° S，并继续向东至少到大西洋中脊。一旦越过海脊，它将沿沿着海脊侧翼向北绕行，然后返回安哥拉盆地东半部的南部。这些数据表明，北大西洋公约组织随后继续进入印度洋。该方案的背景下，溶解氧，硅酸盐和盐度的分布进行了讨论。尽管在该地区收集了许多浮动年的数据，但令人惊讶的是，它们对计算解决方案的影响相当温和。虽然重点是NADW，但我们也讨论了AAIW和AABW层的环流。
Several large deployments of neutrally buoyant floats took place within the Antarctic Intermediate (AAIW), North Atlantic Deep Water (NADW), and the Antarctic Bottom Water (AABW) of the South Atlantic in the 1990s and a number of hydrographic sections were occupied as well. Here we use the spatially and temporally averaged velocities measured by these floats, combined with the hydrographic section data and various estimates of regional current transports from moored current meter arrays, to determine the circulation of the three major subthermocline water masses in a zonal strip across the South Atlantic between the latitudes of 19°S and 30°S. We concentrate on this region because the historical literature suggests that it is where the Deep Western Boundary Current containing NADW bifurcates. In support of this notion, we find that a net of about 5 Sv. of the 15–20 Sv that crosses 19°S does continue zonally eastward at least as far as the Mid-Atlantic Ridge. Once across the ridge it takes a circuit to the north along the ridge flanks before returning to the south in the eastern half of the Angola Basin. The data suggest that the NADW then continues on into the Indian Ocean. This scheme is discussed in the context of distributions of dissolved oxygen, silicate and salinity. In spite of the many float-years of data that were collected in the region a surprising result is that their impact on the computed solutions is quite modest. Although the focus is on the NADW we also discuss the circulation for the AAIW and AABW layers.