Fourth International Planetary Dunes Workshop (2015) 8012.pdf Experimental and numerical study of Sharp's shadow zone hypothesis on sand ripples spacing and implica- tion for Martian sand ripples. H. Yizhaq1,2, E. Schmerler3, I. Katra3 , H. Tsoar3 and J. Kok4. 1Swiss Institute for Dryland Environmental and En- ergy Research, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990, Israel (
[email protected]), 2The Dead Sea and Arava Science Center. Tamar Regional Council, Israel, 3The Department of Geography and Environmental Development, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel, (
[email protected]), (
[email protected]), (
[email protected]). 4Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California, USA, (
[email protected]). Introduction: Although many works have been Materials and Methdes: Quartz sand collected done on sand transport by saltation and reptation, and from the northwestern Negev dunefield (Israel) was on the formation of sand ripples, it is still unclear what used for the laboratory wind tunnel experiments on mechanism determines the linear dependence of ripples ripple morphology. The sand was taken in the sampling dimension on wind speed [1]. We thoroughly studied site in the northern Negev– Sekher (in southeren Israel) the formation of normal ripples in a wind tunnel as a sands from the upper 10 cm of the sand dunes. Com- function of grains size and wind speed. A linear rela- mon sizes of the active (loose) sand in Sekher site are tionship between the wind shear velocity and the im- at the range of 100-400 µm with modes of 150-200 pact angle of saltating grains has been found for differ- µm, which are typical of dune saltators.