In the marignal zone of the sea ice melting of ice depends in the
large degree on the mixing processes in the ocean underneath. Anders
Sirevaag PhD thesis presents the findings he's made in the Arctic.
Anders Sirevaag defended his thesis ”Small-Scale dynamics of the
under-ice boundary layer” at Geophysical Institute, University of Bergen
in January 2009. The thesis focuses on a set of high resolution
measurements of currents and variations in salinity and temperature
under the drifting sea ice. These measurements have been made in close
cooperation with the University Centre on Svalbard (UNIS) in Fram
Strait, Yermak Plateu and north of Svalbard.
Presence of sea ice is
important for the exchange between ocean and the atmosphere. The ice
creates a cover on surface of the ocean, but the properties of the
drifting sea ice are also important for mixing and exchange processes
below the ice. These processes are important when it comes to e.g. how
fast sea ice is melting.
Mixing processes under the sea ice control how efficiently oceanic
heat is transported upwards through the boundary layer and towards the
sea ice. However, melting of sea ice is not only dependent on the amount
of heat below the ice, but also on how efficiently heat is
transferred across the interface between the ocean and the ice, compared
to salt. This difference in transfer rate is called double diffusion. In
areas where melting rates are large, which they typically are north of
Svalbard, this effect tends to limit melting of sea ice and it is
important to incorporate these effects in future estimates of melting
The study also address how large is vertical exchange between ocean and
ice in different areas in Fram Strait and north of Svalbard and how much
heat is exchanged between the different layers in the ocean. This is
important to monitor changes in water masses on their way through the
Fram Strait into the Arctic.
The study provides insight into processes that are important for the
interaction between ocean, ice and atmosphere, both when it comes to
understanding the present and to predicting future climate.
(Source: Anders Sirevaag)
Treg smelting i polare utkantstrøk (Forskning.no);
saktere enn antatt (Yr.no) Both articles are in Norwegian only.
Contact: Anders Sirevaag (Anders.Sirevaag@bjerknes.uib.no)
Fieldwork on sea ice (both photos: Anders Sirevaag)