A longstanding problem in glaciology has been trying to understand how snow is blown around by the wind. The process itself will be familiar to anyone who has been out in the snow on a really windy day, and noticed that great quantities of snow are picked up by the wind and driven into any gap in one’s clothing. On larger scales, the difficulty comes with the sheer quantity of snow that can be moved around by the wind. We can use climate models to determine how much snow falls in any particular area as precipitation, and ice cores to measure the amount of snow that eventually accumulates in the same place, but these two quantities differ because so much snow is moved around before it finally comes to rest. In the past, the only way to measure the rate at which snow is blown past a particular point was to use a fine-meshed “butterfly net”, but this primitive apparatus is not ideal, especially as it requires continuous attention during severe blizzards. Ice2sea researchers have found that an instrument developed to measure precipitation rates in temperate climates can be modified to measure blowing snow, even in the cold of Antarctica. The instrument makes two measurements, one of how snow particles scatter light, and the other determines the relationship between the velocity and size of the particles. Both measurements can be used to discriminate between rain and snow, and allow determination of the volume of snow contained in a particular volume of air. The technique was developed at a test site in the French Alps, and is now undergoing development in Antarctica. The routine measurement of blowing snow will lead the way to a much more effective inclusion of blowing snow in climate models and a much more direct comparison of models of Antarctic climate with observations.
Ice2sea Work Package: WP2.4
Publication: Bellot et al. (2010) Bellot, H., A. Trouvilliez, F. Naaim-Bouvet, C. Genthon, and H. Gallée (2011), Present weather sensors tests for measuring drifting snow, Annals of Glaciology, 52, 179-184.