Real barchan dune collisions and ejections

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Hugenholtz, Chris H.
Barchyn, Thomas E.
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Blackwell Publishing Ltd.
From high-resolution satellite imagery of barchan sand dunes, we provide geomorphological evidence of collisions that result in the ejection of a barchan from the wake of another barchan dune. Previous interpretations suggest this outcome is evidence of soliton or solitary wave behaviour; however, the physical mechanisms for mass exchange are not fully understood, resulting in debate. Our evidence and interpretation indicates that mass is transferred to the upwind barchan by shadowing a portion of downwind barchan's stoss slope. Turbulent, unsaturated airflow erodes the surface between the dunes, creating a smaller dune that ejects from the wake region. Previous observations lacked the spatial resolution required to document this process; therefore, our observations clarify the collision dynamics of barchans. A broader implication of our observations is the role of collisions in maintaining an equilibrium size distribution in barchan swarms.
Sand dunes--Erosion , Climate change , Sand dunes--Remote sensing , Geomorphology , Hydrology , Barchan swarms
Hugenholtz, C.H., Barchyn, T.E., 2012. Real barchan dune collisions and ejections. Geophysical Research Letters 39, L02306.