The edge of the White Sands dune field in New Mexico transitions abruptly from sand to a dune-free area where grass grows. The wind pushes the sand around within the 400-square-kilometer dune field, so much so that the sandy dunes are said to “migrate.” But the line between dunes and vegetation has remained relatively stable for 60 years: The dunes near the edge of the field seem to stay put. A new study from Pelletier and Jerolmack reveals why.
The authors took advantage of recent advances in laser scanning technology and surveyed the area near the dunes’ edge over a 3-month period. From that data, they were able to determine how much the sand was moving. Closer to the dune-vegetation line, the amount the sand was moving decreased. Next, they used a numerical model to investigate the aerodynamics of the dunes and the force the wind exerts on the sand. They found that closer to the edge of the dune, the pressure from the wind reduced and the velocity of the displaced sand slowed.
The authors concluded that the crest of the dunes upwind from the edge shielded the sand. The improved understanding of the evolution of the dunes at White Sands may increase our understanding of dune evolution in general—perhaps even of the dunes that have been imaged on Titan and Mars. (Journal of Geophysical Research: Earth Surface, doi:10.1002/2014JF003210, 2014)
—Shannon Palus, Freelance Writer
Citation: Palus, S. (2015), Exploring how wind blows sand on dunes, Eos, 96, doi:10.1029/2015EO023949. Published on 16 February 2015.