Dense water plumes SW off Spitsbergen Archipelago (Arctic) in 2014-2016


Contact
Thomas.Soltwedel [ at ] awi.de

Abstract

The Arctic region has gained a large interest because of climate changes and its effects on ice melting and global warming. Abrupt changes in the atmosphere are responsible for significant changes in the ocean water masses and large-scale circulation, which in turn affect again the global climate. The knowledge of the circulation and related processes along the southwest (SW) offshore Svalbard area and within Storfjorden (southern Svalbard Archipelago) is essential to describe the thermohaline circulation and the dense water formation (DWF) in the Arctic, and how they contribute to the global thermohaline circulation. DWF processes in this region depend on the rate of cooling and homogenisation of the Atlantic water along its northwards pathway, the brine rejection, boundary convection on the Arctic Ocean shelves and slopes, and the deep open-ocean convection in the central gyres of the Greenland and Iceland Seas. Here, we focus on the brine rejection, shelf convection and entrainment processes, which happen on the west shelf/slope of Svalbard and in the Storfjorden during the winter season. Two short (130m) moorings (S1 and I2) were deployed in 2014 in the SW offshore Svalbard at ~1000m depth, with the purpose of collecting multiannual time-series in an area of potential interaction between the Western Spitsbergen Current and the dense shelf plumes. Three oceanographic cruises were carried out to integrate time-series with CTD casts in the area. One purpose of this research activity was to combine geophysical and oceanographic data to study the interaction of bottom currents and sediment drifts (contourites) formations. At S1 and I2, time-series revealed a large thermohaline and current variability during the winter period, from October to April. Our data highlight the presence of a stable signal of Norwegian Sea Deep Water influenced by occasional intrusions of warmer, saltier, and less dense water during fall-winter periods. Interestingly, such intrusions occur simultaneously at both sites, despite their distance (~170km). We discuss the origin, timing, and role of shelf turbidity plumes (denser than TS plumes), which descend along slope and undergo a strong entrainment process that modify their properties. The role of possible mesoscale processes is also investigated.



Item Type
Conference (Talk)
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Divisions
Primary Division
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Peer revision
Not peer-reviewed
Publication Status
Published
Event Details
IAPSO-IAMAS-IAGA Congress, 27 Aug 2017 - 01 Sep 2017, Cape Town, South Africa.
Eprint ID
44256
Cite as
Bensi, M. , Langone, L. , Kovacevic, V. , Ursella, L. , Rebesco, M. , De Vittor, C. , Aliani, S. , Miserocchi, S. , Relitti, F. , Bazzaro, M. , Deponte, D. , Laterza, R. , Lucchi, R. , Wahlin, A. , Soltwedel, T. , Goszczko, I. , Skogseth, R. , Falck, E. and Nilsen, F. (2017): Dense water plumes SW off Spitsbergen Archipelago (Arctic) in 2014-2016 , IAPSO-IAMAS-IAGA Congress, Cape Town, South Africa, 27 August 2017 - 1 September 2017 .


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