South Atlantic overturning circulation at 24°S
South Atlantic overturning circulation at 24°S
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DOI：
10.1357/002224011798147633
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发表时间：
2011
影响因子：
0.5
通讯作者：
H. Bryden;B. King;G. McCarthy
中科院分区：
文献类型：
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作者：
H. Bryden;B. King;G. McCarthy
为了估计南大西洋纬向翻转环流和纬向热量和淡水输送的大小，我们在2009年沿沿着24°S制作了一个新的跨大西洋水文剖面，并将由此产生的输送与1983年制作的历史剖面的估计值进行了比较。两个断面的倾覆量估计为21.5 Sv（2009年）或16.5 Sv（1983年），热量输送为0.7 PW（2009年）或0.4 PW（1983年）向北，淡水输送较小但向北，为0.04 Sv（2009年）或0.17 Sv（1983年）。运输的差异主要是由于在占领的部分，4.9 Sv（2009年）或12.3 Sv（1983年）的向南巴西流运输的强度不同。用两种不同的方法估算了这两个断面上与纬向翻转环流有关的淡水输运，结果表明，这两个断面上的淡水输运都是向南的，范围在-0.09 ~-0.34Sv之间，这意味着大西洋纬向翻转环流在24°S处向南输送淡水。根据理论研究，这种在大西洋南部边界向南的淡水输送意味着，目前的大西洋环流具有多种平衡状态，它目前所占据的平衡状态可能对足够大的淡水事件不稳定。
To estimate the size of the meridional overturning circulation and the meridional heat and freshwater transports in the South Atlantic, we made a new transatlantic hydrographic section along 24°S in 2009 and we compare the resulting transports with those estimated for a historical section made in 1983. For the two sections, the overturning is estimated to be 21.5 Sv (2009) or 16.5 Sv (1983), the heat transport is northward at 0.7 PW (2009) or 0.4 PW (1983), and the freshwater transport is small but northward at 0.04 Sv (2009) or 0.17 Sv (1983). The differences in transports are primarily due to the different strengths of the southward Brazil Current transport during the occupation of the sections, 4.9 Sv (2009) or 12.3 Sv (1983). The freshwater transport associated with the meridional overturning circulation is estimated by two different methods for each of the two sections and is always southward ranging from -0.09 Sv to -0.34 Sv which means that the Atlantic meridional overturning circulation transports freshwater southward at 24°S. On the basis of theoretical studies, such southward freshwater transport at the southern boundary of the Atlantic Ocean means that the present Atlantic circulation has multiple equilibrium states, and that the one it occupies at present may be unstable to a sufficiently large freshwater event.