Measurements of the Turbulent Oceanic Boundary Layer under Sea Ice

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(1)Measurements were made of the three-dimensional current, temperature and salt regime in the frictional boundary layer under Landfast ice in southeast Hudson Bay during late April, 1990. Time series of currents, momentum, heat and salt fluxes were continuously recorded in the boundary layer during a diurnal tidal period by a three-dimensional ultrasonic current meter and a conductivity-temperature sensor. It was indicated that variations in current at higher frequencies than tides corresponded to those in momentum flux, and that the flow regime in the boundary layer might change intermittently from smooth to rough flow.(2)From turbulence measurements by a three-dimensional ultrasonic. anemometerthermometer estimates of momentum and heat fluxes were derived over both an artificial pool on the ice, approximately 2.2 x 2.2 m and over relatively smooth, snow-covered ice on Elson Lagoon, Alaska in May, 1991. It was indicated that the heat flux coefficient decreased after sea ice was formed on the pool, and that it then increased gradually with an increase in ice thickness. It can be considered that the measurements at 0.4 m height were made within the internal boundary layer over the pool, while those at the 0.96 m height might be affected by the smooth, snowcovered ice upwind of the experimental site.(3)Simultaneous measurements of both atmospheric and oceanic boundary layers through sea ice were made at an artificial pool, approximately 3 x 3 m on Saroma Lagoon, Hokkaido during mid-February to mid-March, 1992. Estimates of momentum, heat, CO2 and salt fluxes will be derived for both open water and thin ice on the pool in conjunction with ice growth. Those data have been in process of analysis.