Observed decline of the Atlantic meridional overturning circulation 2004–2012
Observed decline of the Atlantic meridional overturning circulation 2004–2012
复制标题
DOI：
10.5194/os-10-29-2014
复制
发表时间：
2013-09
期刊：
影响因子：
3.2
通讯作者：
D. Smeed;G. McCarthy;S. Cunningham;E. Frajka‐Williams;D. Rayner;W. Johns;C. Meinen;M. Baringer;B. Moat;A. Duchez;H. Bryden
中科院分区：
文献类型：
--
作者：
D. Smeed;G. McCarthy;S. Cunningham;E. Frajka‐Williams;D. Rayner;W. Johns;C. Meinen;M. Baringer;B. Moat;A. Duchez;H. Bryden
摘要。2004年4月以来，大西洋经向翻转环流（AMOC）在26°N连续观测到。AMOC及其组成部分通过将跨大西洋系泊仪器阵列与海底电缆测量墨西哥湾流和卫星导出的Ekman传输相结合进行监测。最近将时间序列延长至2012年10月，结果显示自2004年以来呈下降趋势。从2008年4月到2012年3月，AMOC比观测的前四年平均弱2.7 Sv (1 Sv = 106 m3 s−1)（95%置信度为0.3 Sv或更多）。Ekman输运减少约0.2 Sv，墨西哥湾流减少约0.5 Sv，但大部分变化（2.0 Sv）是由于大洋中地转流。洋中地转流的变化代表了温跃层上方向南流动的加强。3000米以下北大西洋深水南下流的减少抵消了暖水南下流的增加。北大西洋深水的输送以每年7%的速度减缓（95%的置信度认为减缓速度大于每年2.5%）。
Abstract. The Atlantic meridional overturning circulation (AMOC) has been observed continuously at 26° N since April 2004. The AMOC and its component parts are monitored by combining a transatlantic array of moored instruments with submarine-cable-based measurements of the Gulf Stream and satellite derived Ekman transport. The time series has recently been extended to October 2012 and the results show a downward trend since 2004. From April 2008 to March 2012, the AMOC was an average of 2.7 Sv (1 Sv = 106 m3 s−1) weaker than in the first four years of observation (95% confidence that the reduction is 0.3 Sv or more). Ekman transport reduced by about 0.2 Sv and the Gulf Stream by 0.5 Sv but most of the change (2.0 Sv) is due to the mid-ocean geostrophic flow. The change of the mid-ocean geostrophic flow represents a strengthening of the southward flow above the thermocline. The increased southward flow of warm waters is balanced by a decrease in the southward flow of lower North Atlantic deep water below 3000 m. The transport of lower North Atlantic deep water slowed by 7% per year (95% confidence that the rate of slowing is greater than 2.5% per year).