| Direct wind resuspension provides a source of dust to the atmosphere, where the particles may pose a risk to human health, mediate chemical reactions, act on global climate, and transport environmental contaminants. Predicting the dust flux under various atmospheric and surface conditions has proven difficult, with field data showing great variability.; Certain dust flux models assume that direct wind resuspension occurs only for high wind events and then only transiently, with a short-term flux occurring only when the surface is first exposed to the high wind. In the longer term, the surface is assumed to stabilize, with no further dust released until the surface is mechanically or physically disturbed or exposed to a higher wind. Other, more general models describe a surface in terms of a threshold velocity, such that no material is removed until the threshold is exceeded. The hypothesis of this investigation is that there are small but steady dust fluxes below the threshold velocity and after the initial transients. |
