Geostrophic drag coefficients over sea ice

The geostrophic drag coefficient, Cg = u_*/G, and turning angle, α were measured October through November 1988 from a 120 km array of 6 drifting buoys and a drifting ship in the northern Barents Sea/Arctic Ocean during CEAREX; u_* is the friction velocity, G is the geostrophic wind, and α is the angle between surface stress and equation image . The median Cg was 0.029 with hinge values (quartiles) of 0.023 and 0.034 and the median α was 25° with hinge values of 15° and 32°. The median values are representative for the nonsummer Arctic away from marginal seas and marginal ice zones. Surface air temperature, cloud amount, and the lapse rate above the inversion base were not good predictors of the influence of boundary layer stability on Cg. The geostrophic drag coefficient was most sensitive to the temperature difference across the boundary layer from the surface to the top of the inversion.