The Emergence of the North Icelandic Jet and Its Evolution from Northeast Iceland to Denmark Strait
The Emergence of the North Icelandic Jet and Its Evolution from Northeast Iceland to Denmark Strait
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DOI：
10.1175/jpo-d-19-0088.1
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发表时间：
2019-10-01
影响因子：
3.5
通讯作者：
Jonsson, Steingrimur
中科院分区：
文献类型：
--
作者：
Semper, Stefanie;Vage, Kjetil;Jonsson, Steingrimur
北冰岛急流（NIJ）是流经丹麦海峡的溢流柱的重要浓水来源。利用2004年至2018年间进行的13次高空间分辨率水文/速度调查，首次沿着冰岛北部大陆坡的整个路径研究了NIJ的性质、结构和运输。综合数据集显示，海流起源于冰岛东北部，流量每100 km增加约0.4 Sv（1 Sv相当于10（6）m（3）s（-1）），直到丹麦海峡上游300 km处，此时流量达到最高。NIJ传输的大部分局限于Theta-S空间中的一个小区域，中心位置在保守温度下为-0.29度+/- 0.16摄氏度附近，绝对盐度下为35.075 +/- 0.006 g kg（-1）。虽然这种传输模式的水文特性没有显着修改沿着NIJ的路径，运输估计之间和调查内有很大的差异。既没有一个明确的季节性信号，也没有一致的联系，大气强迫被发现，但正压和/或斜压不稳定可能是活跃的电流。NIJ在大约50%的职业中显示出双核结构，两个核心分别集中在600米和800米等深线。在丹麦海峡上游300公里处，溢流水的输送量超过1.8 +/- 0.3 Sv，这大大超过了在NIJ与分离的东格陵兰海流汇合处，通过长达一年的系泊阵列和靠近海峡的水文/流速调查得出的估计值。这意味着NIJ对丹麦海峡溢流羽流的贡献比以前设想的更大。
The North Icelandic Jet (NIJ) is an important source of dense water to the overflow plume passing through Denmark Strait. The properties, structure, and transport of the NIJ are investigated for the first time along its entire pathway following the continental slope north of Iceland, using 13 hydrographic/velocity surveys of high spatial resolution conducted between 2004 and 2018. The comprehensive dataset reveals that the current originates northeast of Iceland and increases in volume transport by roughly 0.4 Sv (1 Sv equivalent to 10(6) m(3) s(-1)) per 100 km until 300 km upstream of Denmark Strait, at which point the highest transport is reached. The bulk of the NIJ transport is confined to a small area in Theta-S space centered near -0.29 degrees +/- 0.16 degrees C in Conservative Temperature and 35.075 +/- 0.006 g kg(-1) in Absolute Salinity. While the hydrographic properties of this transport mode are not significantly modified along the NIJ's pathway, the transport estimates vary considerably between and within the surveys. Neither a clear seasonal signal nor a consistent link to atmospheric forcing was found, but barotropic and/or baroclinic instability is likely active in the current. The NIJ displays a double-core structure in roughly 50% of the occupations, with the two cores centered at the 600- and 800-m isobaths, respectively. The transport of overflow water 300 km upstream of Denmark Strait exceeds 1.8 +/- 0.3 Sv, which is substantially larger than estimates from a year-long mooring array and hydrographic/velocity surveys closer to the strait, where the NIJ merges with the separated East Greenland Current. This implies a more substantial contribution of the NIJ to the Denmark Strait overflow plume than previously envisaged.