Vertical profiles of snowdrift density and concurrent meteorological data were measured over Antarctic snow and blue ice during a 1 month field experiment in austral summer 1997/98. It is found that drift densities and transport rates over blue ice are significantly smaller than over snow, which can be attributed mainly to the limited availability of snow particles at the blue-ice surface. Hence, over blue ice, near-surface drift densities and vertical gradients in drift density are relatively small. Over blue ice, snowdrift can occur in very weak winds, presumably because of the smoothness of the surface. Over snow, in contrast, drift occurs only in much stronger winds, such that the shear stress applied by the flow can overcome the cohesive interparticle bonds.

For the study of drifting snow a pulse-counting device was developed. The detector is sensitive to the momentum transfer of individual snow particles to an exposed surface. More than 105 particles can be counted per cm2/s. The sensor is adjusted to snow particles of 30–200 μm in diameter and a velocity range of 5–30 m/s. A multi-channel analyzer system is used for data handling and to display the momentum spectrum in real time.

A photon-counting system with a 512-channel parallel output digital image tube is presented. Electronics developped separately for each detector channel as well as data aquisition are optimized for low power consumption and high count rates. This detector, characterized by wide dynamic range, very low noise and high photo-metric accuracy, is especially suitable for spectrophotometry and calibrations.