A study of the roughness parameters of sea ice from wind profiles

Measurements of wind speed at five heights in geometric progression to a maximum of 4 meters were made in the Arctic for a 3-week period in the spring of 1971 at the junction of two ice floes of differing surface morphology. About 150, or 30%, of the 1-hour wind profiles conformed to the requirements of conditions of near-neutral stratification of the boundary layer. Values of roughness length z0 and of drag coefficient C10 for the wind at the 10-meter level were found to vary with wind direction, depending on whether the wind reached the site after flowing over relatively smooth ice or over rough ice. For an upwind fetch over smooth ice in the sectors 52°–63° and 77°–115°, z0 had average values of 0.051 and 0.053 cm, and C10 had values of (1.66 ± 0.08) × 10−3 and (1.69 ± 0.05) × 10−3. When the upwind fetch was over the rough ice from the sectors 240°–283° and 284°–327°, the corresponding values of z0 were 0.28 and 0.30 cm, and the values for C10 were (2.42 ± 0.06) × 10−3 and (2.46 ± 0.04) × 10−3.