Spitsbergen Oceanic and Atmospheric interactions

• Main Authors: Bensi, M, Kovacevic, V, Ursella, L, Rebesco, M, Langone, L, Viola, A, Mazzola, M, Beszczyńska- Möller, A, Goszczko, I, Soltwedel, T, Skogseth, R, Nilsen, F, Wåhlin, A
• Format: Report
• Language: English
• Published: Zenodo 2019
• Subjects: Fram strait; deep sea thermohaline variability; slope currents; wind-induced processes; Arctic; Svalbard; Fram Strait; Svalbard margin; Spitsbergen
• Online Access: https://dx.doi.org/10.5281/zenodo.4778405; https://zenodo.org/record/4778405

This is chapter 6 of the State of Environmental Science in Svalbard (SESS) report 2018 (https://sios-svalbard.org/SESS_Issue1). In the Fram Strait, a remarkable increase in the temperature and salinity of inflowing Atlantic Water has been observed since the 1990s. This is in part a natural trend, but recent temperature anomalies, ~1°C relative to the 1970s are related to anthropogenic causes. Air temperature increased by about 3°C in the 20th century and meteorological stations at Svalbard confirm this positive trend. At the West Spitsbergen margin, Atlantic and Arctic waters converge, mix and exchange, while air–sea interactions and shelf–slope dynamics trigger vertical mixing and formation of cold and salty water. This water is sufficiently dense to sink to greater depths and contribute to the global thermohaline circulation. The circulation process permits exchange of heat (i.e., energy) between low and high latitudes. Since the formation of dense water and its spreading at greater depths are strongly influenced by the properties of Atlantic Water, which have been changing in the last decades, we cannot exclude the possibility that the global thermohaline circulation may change in the near future. We analysed oceanographic data (obtained from shelf and deep-sea oceanographic moorings and hydrographic cruises) and meteorological data from the west Svalbard margin, comparing temperature and salinity variability in the deep ocean flow and the wind regime. Time-series revealed occasional intrusions of warm and salty waters at 1000 m depth, mainly during the period October – April, quasi-simultaneously at several locations more than 150 apart, along the continental slope west of Svalbard. The fact that the most energetic events, both in the deep flow and in the wind speed, occurred with similar periodicities (10-20 days) suggests atmospheric storms as the likely forcing mechanism underlying the observed deep sea variability. Others energetic events with periodicity of 12 and 24 hours, instead, could be related to internal tidal oscillations. The fact that the most energetic events, both in the deep flow and in the wind speed, had similar periodicities (10-20 days) suggests atmospheric storms as the likely forcing mechanism underlying the observed deep-sea variability. Other energetic events with periodicity of 12 and 24 hours could instead be related to tidal oscillations.