Telling what the weather is like on distant planets might be possible, if they鈥檙e covered in sand dunes. A four-year experiment has revealed how prevailing winds create sand dunes on Earth. The data could enable astronomers to determine weather patterns on other worlds by monitoring wind-formed sand dunes on the surface.
Working in the remote Tengger desert of Inner Mongolia, of the Global Institute for Physics in Paris, France, and his colleagues used a bulldozer to flatten 160,000 square metres of sand dunes in 2008. Over the next three-and-a-half years, they watched the dunes rebuild and closely tracked the accompanying winds.
鈥淭here are very few studies of how sand dunes are initiated and grow,鈥� says of the Desert Research Institute in Reno, Nevada, who was not involved in the research. 鈥淭his field experiment is unique.鈥�
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A line in the sand
Narteau found that the newly-created dunes pointed in directions dictated by two prevailing winds, which buffet the desert at different times of the year. The final orientation of each dune was a compromise between the two wind directions, their durations and their relative strengths.
鈥淎s the dune is growing, each individual wind contributes to its final shape,鈥� says Narteau. 鈥淵ou build up grains perpendicular to each individual wind to build a major structure with an intermediate orientation.鈥�
鈥淲e鈥檝e demonstrated that dunes can be used to derive wind orientations and wind strength,鈥� says Narteau. He now plans to examine dunes on Mars and Titan, the largest moon of Saturn.
鈥淲e don鈥檛 have weather networks yet on Mars or Titan, so the pattern of sand dunes is one of the best indicators we have of winds,鈥� says Ralph Lorenz of Johns Hopkins University in Laurel, Maryland.
Journal reference: Nature Geoscience,
