The emergence of the North Icelandic Jet and its evolution from northeast Iceland to Denmark Strait
Pickart, Robert S.
Torres, Daniel J.
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KeywordOcean; Continental shelf/slope; Ocean circulation; Transport; Intermediate waters; In situ oceanic observations
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 ≡ 106 m3 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 Θ–S space centered near −0.29° ± 0.16°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.
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Semper, S., Vage, K., Pickart, R. S., Valdimarsson, H., Torres, D. J., & Jonsson, S. The emergence of the North Icelandic Jet and its evolution from northeast Iceland to Denmark Strait. Journal of Physical Oceanography, 49(10), (2019): 2499-2521, doi:10.1175/JPO-D-19-0088.1.
Suggested CitationSemper, S., Vage, K., Pickart, R. S., Valdimarsson, H., Torres, D. J., & Jonsson, S. (2019). The emergence of the North Icelandic Jet and its evolution from northeast Iceland to Denmark Strait. Journal of Physical Oceanography, 49(10), 2499-2521.
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Moore, G. W. K.; Våge, Kjetil; Pickart, Robert S.; Renfrew, Ian A. (2015-05-18)The air-sea transfer of heat and freshwater plays a critical role in the global climate system. This is particularly true for the Greenland and Iceland Seas, where these fluxes drive ocean convection that contributes to ...
Pickart, Robert S.; Spall, Michael A.; Torres, Daniel J.; Våge, Kjetil; Valdimarsson, Héðinn; Nobre, Carolina; Moore, G. W. K.; Jonsson, Steingrimur; Mastropole, Dana M. (Sears Foundation for Marine Research, 2017-09-01)Shipboard hydrographic and velocity sections are used to quantify aspects of the North Icelandic Jet (NIJ), which transports dense overflow water to Denmark Strait, and the North Icelandic Irminger Current (NIIC), which ...