Monday, 10 January 2005
Turbulent mixing in the under-ice boundary layer in Van Mijenfjorden (Svalbard), melt season 2004.
The seasonal, land-fast fjord ice on Van Mijenfjorden in the arctic archipelago Svalbard (78 N) offers a relatively easily accessible natural laboratory for under-ice boundary layer and mixing processes studies. Here we present recent data from June 2004 when a one-week field campaign was carried out on relatively rapidly melting ice. Water tenths of a degree above freezing was advected below the ice at speed of around 0.15 m/s leading to melt rates on the order of centimetres per day of the originally ~0.45 m thick ice. Turbulent fluxes of heat, salt and momentum below the ice were measured by the eddy covariance method in 1 and 5 m below the ice. In addition repeated measurements with a loosely-tethered free-fall microstructure profiler were carried out down to 60 m depth, giving vertical profiles of microstructure variations in shear, temperature and conductivity. An acoustic doppler profiler was deployed to monitor the background current and shear. Properties of the turbulent field in the under-ice boundary layer and water column below as represented by these data sets will be presented and discussed.