Transport of volume, heat, and salt towards the Arctic in the Faroe Current 1993-2013
Transport of volume, heat, and salt towards the Arctic in the Faroe Current 1993-2013
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DOI：
10.5194/os-11-743-2015
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发表时间：
2015-01-01
期刊：
影响因子：
3.2
通讯作者：
Osterhus, S.
中科院分区：
文献类型：
--
作者：
Hansen, B.;Larsen, K. M. H.;Osterhus, S.
来自大西洋的暖流和咸水，穿过格陵兰-苏格兰脊，进入北欧海——大西洋流入——被分成三个独立的分支。这些支流中最强烈的是冰岛和法罗群岛（法罗群岛）之间的流入，它集中在法罗群岛以北的法罗洋流。大西洋流入是北大西洋热盐环流（THC）的一个组成部分，预计在21世纪将减弱，并可能减少海洋向北极的热盐输送。自20世纪90年代中期以来，人们一直在法罗陆架向北延伸的一段地区监测法罗洋流的水文特性和流速。根据这些实地观测，以前曾报道过体积、热量和盐传输的时间序列，但传输的高度可变性使得很难确定是否存在趋势。在这里，我们介绍了法罗洋流的新分析结果，其中现场观测与卫星测高相结合。从1993年到2013年，我们发现法罗海流中大西洋水的平均体积输运为3.8 +/- 0.5 Sv (1 Sv = 10(6) m(3) s(1))，相对于0℃的热输运为124 +/- 15TW （1TW = 10(12) W）。与东北大西洋分量的其他结果一致，我们没有发现减弱的迹象。相反，法罗海流的输送量增加了。在20年的观测中，体积输运的总体增幅为9 +/- 8%，热输运的总体增幅为18 +/- 9%（95%置信区间）。同期，法罗深滩溢流（34.93）的盐输运相对于盐度增加了一倍以上，可能加强了对热盐强度的反馈。热盐输送的增加部分是由体积输送的增加引起的，部分是由大西洋流入的温度和盐度的增加引起的，这主要是由亚极环流的减弱引起的。
The flow of warm and saline water from the Atlantic Ocean, across the Greenland-Scotland Ridge, into the Nordic Seas - the Atlantic inflow - is split into three separate branches. The most intense of these branches is the inflow between Iceland and the Faroe Islands (Faroes), which is focused into the Faroe Current, north of the Faroes. The Atlantic inflow is an integral part of the North Atlantic thermohaline circulation (THC), which is projected to weaken during the 21st century and might conceivably reduce the oceanic heat and salt transports towards the Arctic. Since the mid-1990s, hydrographic properties and current velocities of the Faroe Current have been monitored along a section extending north from the Faroe shelf. From these in situ observations, time series of volume, heat, and salt transport have previously been reported, but the high variability of the transport has made it difficult to establish whether there are trends. Here, we present results from a new analysis of the Faroe Current where the in situ observations have been combined with satellite altimetry. For the period 1993 to 2013, we find the average volume transport of Atlantic water in the Faroe Current to be 3.8 +/- 0.5 Sv (1 Sv = 10(6) m(3) s(1)) with a heat transport relative to 0 degrees C of 124 +/- 15TW (1TW = 10(12) W). Consistent with other results for the Northeast Atlantic component of the THC, we find no indication of weakening. The transports of the Faroe Current, on the contrary, increased. The overall increase over the 2 decades of observation was 9 +/- 8% for volume transport and 18 +/- 9% for heat transport (95% confidence intervals). During the same period, the salt transport relative to the salinity of the deep Faroe Bank Channel overflow (34.93) more than doubled, potentially strengthening the feedback on thermohaline intensity. The increased heat and salt transports are partly caused by the increased volume transport and partly by increased temperatures and salinities of the Atlantic inflow, which have been claimed mainly to be caused by the weakened subpolar gyre.