title: Unravelling raked linear dunes to explain the coexistence of bedforms in complex dunefields.
abstract: Raked linear dunes keep a constant orientation for considerable distances with a marked asymmetry between a periodic pattern of semi-crescentic structures on one side and a continuous slope on the other. Here we show that this shape is associated with a steady-state dune type arising from the coexistence of two dune growth mechanisms. Primary ridges elongate in the direction of the resultant sand flux. Semi-crescentic structures result from the development of superimposed dunes growing perpendicularly to the maximum gross bedform-normal transport. In the particular case of raked linear dunes, these two mechanisms produces primary and secondary ridges with similar height but with different orientations, which are oblique to each other. The raked pattern develops preferentially on the leeward side of the primary ridges according to the direction of propagation of the superimposed bedforms. As shown by numerical modelling, raked linear dunes occur where both these oblique orientations and dynamics are met.
authors.affiliation: Department of Geography, Shaanxi Normal University, 620 Chang'an West Avenue, Xi'an, Shaanxsi 710119, China.|Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, 320 West Donggang Road, Lanzhou, Gansu 730000, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Lü
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 1 rue Jussieu, 75238 Paris Cedex 05, France.
authors.forename: Clément
authors.initials: C
authors.lastname: Narteau
authors.affiliation: Department of Geography, Shaanxi Normal University, 620 Chang'an West Avenue, Xi'an, Shaanxsi 710119, China.|Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, 320 West Donggang Road, Lanzhou, Gansu 730000, China.
authors.forename: Zhibao
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, UMR 7154 CNRS, 1 rue Jussieu, 75238 Paris Cedex 05, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Rozier
authors.affiliation: Laboratoire Matière et Systèmes Complexes, Sorbonne Paris Cité, Université Paris Diderot, UMR 7057 CNRS, Bâtiment Condorcet, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Courrech du Pont