Origins of barchan dune asymmetry: Insights from numerical simulations

Eric J.R. Parteli, Orencio Durán, Mary C. Bourke, Haim Tsoar, Thorsten Pöschel, Hans Herrmann

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


Barchan dunes - crescent-shaped dunes that form in areas of unidirectional winds and low sand availability - commonly display an asymmetric shape, with one limb extended downwind. Several factors have been identified as potential causes for barchan dune asymmetry on Earth and Mars: asymmetric bimodal wind regime, topography, influx asymmetry and dune collision. However, the dynamics and potential range of barchan morphologies emerging under each specific scenario that leads to dune asymmetry are far from being understood. In the present work, we use dune modeling in order to investigate the formation and evolution of asymmetric barchans. We find that a bimodal wind regime causes limb extension when the divergence angle between primary and secondary winds is larger than 90°, whereas the extended limb evolves into a seif dune if the ratio between secondary and primary transport rates is larger than 25%. Calculations of dune formation on an inclined surface under constant wind direction also lead to barchan asymmetry, however no seif dune is obtained from surface tilting alone. Asymmetric barchans migrating along a tilted surface move laterally, with transverse migration velocity proportional to the slope of the terrain. Limb elongation induced by topography can occur when a barchan crosses a topographic rise. Furthermore, transient asymmetric barchan shapes with extended limb also emerge during collisions between dunes or due to an asymmetric influx. Our findings can be useful for making quantitative inference on local wind regimes or spatial heterogeneities in transport conditions of planetary dune fields hosting asymmetric barchans.

Original languageEnglish
Pages (from-to)121-133
Number of pages13
JournalAeolian Research
StatePublished - 1 Mar 2014


  • Barchan dunes
  • Dune asymmetry
  • Dune model
  • Sand transport
  • Wind erosion

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes


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