Measurements of wind speed were made between 31 March and 12 April, 1972 with sensitive cup anemometers at five heights in geometric progression from 25 cm to 4 m above the surface of a gently hummocked ice floe at each of two observation masts which were placed 250 m apart at the site of the main camp of the 1972 AIDJEX pilot experiments. The data were averaged for one-hour periods and have been used to determine the air drag coefficient on the 64 occasions when the vertical profile of wind varied logarithmically with height and to study the horizontal homogeneity of the wind field in the boundary layer. Mean values of the drag coefficient, for winds extrapolated to the 10 m level, were 1.58¿10-3 at one location with a standard deviation for an individual value of 0.19¿10-3 and 1.74¿10-3¿0.25¿10-3 at the other. The corresponding values of roughness length zo were 0.043 and 0.069 cm.