Wednesday, 12 January 2005
Characteristics of the turbulent boundary layer under drifting sea ice
Two drift station experiments north of Svalbard during the WARPS (Winter Arctic Polynya Study) cruise in March-April 2003 were established to study properties of the turbulent boundary layer under drifting ice. Data were obtained using an acoustic Doppler current meter together with fast response temperature and salinity sensors, all mounted on a rigid mast to measure turbulent fluctuations in velocity, temperature and salinity at the same vertical level under ice. The German ice breaker FS Polarstern, which was moored to a large ice floe during the drift stations, served as a logistic base and the instruments were deployed well away from the ship in 2-3 m thick, ridge dominated pack ice. The two ice stations represent a wide range of conditions, from ice drifting at speeds of ~15cm/s over a mixed layer with water temperatures ~1 K above freezing at 80 N, to more slowly drifting ice over the eastern slope of the Yermak Plateu with water temperatures close to freezing. Velocity, temperature and salinity data are analyzed in order to obtain the general characteristics of the turbulent boundary layer flow; fluxes of heat, salt and momentum calculated by the covariance method as well as general turbulent properties of the flow under rough, drifting ice calculated using common spectral techniques from the literature.