Sand patches are one of the precursors to early-stage protodunes and occur widely in both desert and coastal aeolian environments. Here we show field evidence of a mechanism to explain the initiation of sand patches on non-erodible surfaces, such as desert gravels and moist beaches. Changes in sand transport dynamics, directly associated with the height of the saltation layer and variable transport law, observed at the boundary between non-erodible and erodible surfaces lead to sand deposition on the erodible surface. This explains how sand patches can form on surfaces with limited sand availability where linear stability of dune theory does not apply. This new mechanism is supported by field observations that evidence both the change in transport rate over different surfaces and in-situ patch formation that leads to modification of transport dynamics at the surface boundary.
Comment on "Distinct Thresholds for the Initiation and Cessation of Aeolian Saltation From Field Measurements" by Raleigh L. Martin and Jasper F. Kok: Alternative Interpretation of Measured Thresholds as two Distinct Cessation Thresholds
Quantifying the form-flow-saltation dynamics of aeolian sand ripples
University of Southampton（南安普顿大学）；Loughborough University（拉夫堡大学）；University of Oxford（牛津大学）；University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；University of Colorado Denver（科罗拉多大学丹佛分校）；Ecole Normale Supérieure（巴黎高等师范学院）；CNRS（法国国家科学研究中心）；PSL Research University（巴黎文理研究大学）；Great Sand Dunes National Park and Preserve, National Park Service（大沙丘国家公园及保护区，美国国家公园管理局）；Astrin Biosciences, Inc.（阿斯特林生物科学公司）；University of Namibia（纳米比亚大学）；ESPCI Paris（巴黎物理化工国立高等学院）；Université Paris Cité（巴黎西岱大学）；Sorbonne Université（索邦大学）
