Overflow of cold water across the Iceland–Faroe Ridge through the Western Valley
Overflow of cold water across the Iceland–Faroe Ridge through the Western Valley
复制标题
冷水通过西谷溢出冰岛-法罗山脊
DOI：
10.5194/os-14-871-2018
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发表时间：
2018
期刊：
影响因子：
3.2
通讯作者：
S. Østerhus
中科院分区：
文献类型：
--
作者：
B. Hansen;K. Larsen;S. Olsen;D. Quadfasel;K. Jochumsen;S. Østerhus
抽象的。冰岛-法罗海脊被认为是
北欧海高密度溢水的第三大重要通道
流入大西洋经向翻转的下肢
体积输送量约为1 Sv（106 m3 s−1）的环流。
西谷是最北端的深水通道，
IFR被认为提供了强大而持久的溢出
（WV-overflow），占整个溢出的很大一部分
IFR。然而，到目前为止，对这种运输的长期测量
失踪了为了通过直接测量来量化流量，
仪器包被部署在西部山谷的岩床附近
278天（2016-2017年），包括声学多普勒海流剖面仪，
溢出核心的预期位置。平均运输量
田间试验期间的WV溢流为（0.02±0.05）
SV.通过观测和两层水力模型，我们认为，
造成这种低值的原因是温暖的大西洋水流入
上层的挪威海抑制了深层溢流。链路
深层流和表层流之间的关系解释了
卫星测高测量的溢流和海平面坡度。这
关系，结合历史水文测量，使我们能够
得出结论，西弗吉尼亚州溢出的体积运输最有可能是
自常规卫星开始以来，平均小于0.1 Sv
1993年的高度测量。我们新的直接测量不允许我们提出一个
更新了整个IFR的总溢出估计，但它们表明，
它可能远远小于1 Sv。
Abstract. The Iceland–Faroe Ridge (IFR) is considered to be the
third most important passage for dense overflow water from the Nordic Seas
feeding into the lower limb of the Atlantic Meridional Overturning
Circulation with a volume transport on the order of 1 Sv (106 m3 s−1).
The Western Valley, which is the northernmost deep passage across
the IFR, has been presumed to supply a strong and persistent overflow
(WV-overflow), contributing a large fraction of the total overflow across
the IFR. However, prolonged measurements of this transport are so far
missing. In order to quantify the flow by direct measurements, three
instrumental packages were deployed close to the sill of the Western Valley
for 278 days (2016–2017) including an acoustic Doppler current profiler at
the expected location of the overflow core. The average volume transport of
WV-overflow during this field experiment was found to be (0.02±0.05)
Sv. Aided by the observations and a two-layer hydraulic model, we argue that
the reason for this low value is the inflow of warm Atlantic water to the
Norwegian Sea in the upper layers suppressing the deep overflow. The link
between deep and surface flows explains an observed relationship between
overflow and sea level slope as measured by satellite altimetry. This
relationship, combined with historical hydrographic measurements, allows us
to conclude that the volume transport of WV-overflow most likely has been
less than 0.1 Sv on average since the beginning of regular satellite
altimetry in 1993. Our new direct measurements do not allow us to present an
updated estimate of the total overflow across the IFR, but they indicate
that it may well be considerably less than 1 Sv.