Vorticity waves and heat loss in the ocean outside Svalbard

Vorticity waves and heat loss in the ocean outside Svalbard

Top image: CTD measurements taken onboard R/V Lance. Photo: Kjersti Lundmark Daae/UNIS

Sigurd Henrik Teigen has investigated heat loss processes in the West Spitsbergen Current outside Svalbard. Through idealized calculation models he has investigated the importance of flow instability for the cooling of the current. His study contributes to the quantification of the processes that modify the warm core of the current before it reaches the ice covered Polar Ocean. Teigen defends his PhD thesis on 16 June.

14 June 2011
Press release from UNIS and the University of Bergen

The West Spitsbergen Current is an extension of the Gulf Stream that transports warm and salty Atlantic water northward along the continental shelf bank west of Svalbard. The warm water has significance for the sea ice coverage in the area, while the salt is an important ingredient in the deep water formation that drives the Gulf Stream. In order to understand the role of the West Spitsbergen Current in future climate changes, it is vital to get a clear picture of the underlying natural processes which affects the water in the current.

The vorticity (eddy) activity in the ocean is one of the mechanisms that contribute to the cooling of the Atlantic water on its path around Svalbard. Teigen has employed idealized calculation models to investigate the formation of unstable vorticity waves over the continental shelf bank outside Svalbard. The input to the models has been based on measurements of current velocity, salinity and temperature of the West Spitsbergen Current.

The vorticity waves bring warm water from the core of the current up to the ocean surface, where it is efficiently cooled by the atmosphere. The waves also mix the warm water with the surrounding cooler and fresher polar water masses. The calculation models give answers to what properties (for example wave length, wave period and position) characterize the vorticity waves outside Svalbard.

Teigen’s investigations show that the unstable vorticity waves are more active during the winter time, when the current is stronger. He has also compared the vorticity waves’ contribution to heat loss with the direct heat loss to the atmosphere and heat loss as a consequence of ice melting.  One of his results shows that the general decline in sea ice coverage in the Arctic over the last couple of years manifests itself through the reduced importance of ice melting for the West Spitsbergen Current before it reaches the Polar Ocean.

Dissertation
Sigurd Henrik Teigen will defend his PhD thesis ”Water mass exchange in the sea west of Svalbard – A process study of flow instability and vorticity generated heat fluxes in the West Spitsbergen Current”, at UNIS on 16 June at 13:15. He will give a trial lecture entitled “The Atlantic Water influence on the Arctic Ocean ice cover” on the same day at 10:15.

Sigurd Henrik Teigen.

Sigurd Henrik Teigen.

About the candidate:
Sigurd Henrik Teigen (born 1980) is from Trondheim, Norway. He completed a master in technology with specialization in technical physics from the Norwegian University of Science and Technology (NTNU) in 2005.

In 2007 he enrolled as a PhD student at the University Centre in Svalbard (UNIS) and the University of Bergen.

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