Transverse dunes appear in regions of mainly unidirectional wind and high sand availability. A dune model is extended to two dimensional calculation of the shear stress. It is applied to simulate dynamics and morphology of transverse dunes which seem to reach lateral invariance and do not stop growing. Hence, simulations of two dimensional dune fields have been performed. Characteristic laws we...

Introduction: Exotic sand dunes on Mars have been known since 1972 when NASA's Mariner 9 spacecraft transmitted images of their interesting shapes. This is a common feature across the surface of Mars. Despite three decades of studying these features [e.g., 1-16], many questions remain regarding their composition, sources of sediment, morphology, age , origins, and dynamics under present and pas...

Sand dunes are beautiful sand patterns formed by the wind, and have been seen in many places on Mars. In particular barchan dunes, which have a crescent shape, propagate on solid ground under unidirectional winds and are very common on earth’s deserts and coasts, have been observed forming corridors on the floor of martian craters and also on the north pole. However, barchan dunes on Mars have ...

Sand dunes are often covered by vegetation and biogenic crusts. Despite their significant role in dune stabilization, biogenic crusts have rarely been considered in model studies of dune dynamics. Using a simple model, we study the existence and stability ranges of different dune-cover states along gradients of rainfall and wind power. Two ranges of alternative stable states are identified: fix...

Optical and radiocarbon dating indicates that alluvium underlying dunes near Abilene was deposited at or before 45 ka, and that the overlying dunes were active at 1.1–0.5 ka. Geochemical data indicate that the Abilene dune sand is immature and was derived from the underlying Pleistocene alluvium, and not from Holocene age Smoky Hill River deposits. These findings suggest that dune activation wa...

Sand hill environments in the Canadian grasslands can be classified as sandstone outcrops, upland dunes, sand features associated with water, non-human disturbances, anthropogenic disturbances, beach dunes, or sandbars. Insects and other arthropods use these environments for burrow construction, access to sand-associated host plants, open ground predation and scavenging, thermoregulation, and l...

A simple model for the dynamics of dunes associated with vegetation is proposed. Using the model, formation processes of transverse dunes, parabolic dunes and elongated parabolic dunes according to two environmental factors: i)the amount of sand at the source,ii)the wind force, are simulated. The results have qualitative correspondence to the real counterpart, and the simplicity of the algorith...

The engineering interest about dune fields is dictated by the their interaction with a number of human infrastructures in arid environments. Sand dunes dynamics is dictated by wind and its ability to induce sand erosion, transport and deposition. A deep understanding of dune aerodynamics serves then to ground effective strategies for the protection of human infrastructures from sand, the so-cal...

Introduction The volumetric transport rate of sand, or flux, is a fundamental parameter that controls the rate of landscape modification. This process is responsible for the movement of ripples and dunes, as well as the abrasion of rocks and landforms. Measuring sand flux on Mars was previously not possible because of the lack of high spatial and temporal resolution images, and appropriate tech...

Here we discuss the application of an edge detection filter, the Sobel filter of GIMP, to the recently discovered motion of some sand dunes on Mars. The filter allows a good comparison of an image HiRISE of 2007 and an image of 1999 recorded by the Mars Global Surveyor of the dunes in the Nili Patera caldera, measuring therefore the motion of the dunes on a longer period of time than that previ...