FY 1984

Bering Air-Sea-Ice Study (BASICS), February and March 1981

Macklin, S.A., C.H. Pease, and R.M. Reynolds

NOAA Tech. Memo. ERL PMEL-52, NTIS: PB84-196161, 104 pp (1984)

An air-sea-ice interaction experiment was conducted in the eastern Bering Sea during late February and early March 1981. Observations of the atmospheric surface layer were made from a buoy anchored 100 km seaward of the ice edge, from a ship steaming in the marginal ice zone (MIZ), and from an instrumented tower erected 100 km into the ice pack. During typical off-ice wind conditions the atmospheric surface layer was found to warm and accelerate with passage over the MIZ. Observations of the atmospheric boundary layer made from sondes launched from the ship in the MIZ showed a gradual warming and rising of the mixed layer with off-ice winds. Oceanic profiles of density and temperature conducted from the ship indicated a homogeneous column seaward of the ice edge, a two-level system under the MIZ with a mixed layer of oceanic water lying below a cooler, fresher lens of water beneath the ice and a homogeneous column north of the MIZ. Near-surface current meter profiles conducted from the within-pack station verified the presence of a sub-ice logarithmic boundary layer. Wind tower and current meter measurements generated estimates of air and water drag coefficients for the ice of 3.09 × 10 at 10 m and 14.7 × 10 at –2 m, respectively. The ice floes in the vicinity of the station were tracked for about 2 weeks until they reached the ice edge and melted. Tidal forces were seen to be an important component in the motion of ice floes. Floes were also observed to accelerate as they approached the ice edge.