نتایج جستجو برای: sand dunes

تعداد نتایج: 29226  

Journal: :Geophysical Research Letters 2012

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2013
Orencio Durán Laura J Moore

Coastal dunes, in particular foredunes, support a resilient ecosystem and reduce coastal vulnerability to storms. In contrast to dry desert dunes, coastal dunes arise from interactions between biological and physical processes. Ecologists have traditionally addressed coastal ecosystems by assuming that they adapt to preexisting dune topography, whereas geomorphologists have studied the properti...

2005
G. N. LOUW S. W. NICOLSON M. K. SEELY G. N. Louw

The massive dune sea of the southern Namib Desert is approximately 800 km in length and some 140 km wide. These dunes are among the highest in the world and, in spite of very sparse vegetation cover, they support a surprising variety of reptiles and arthropods (Koch, 1961; Louw & Seely, 1982). A feature of the arthropod fauna is the high species diversity of flightless tenebrionid beetles. Thes...

Journal: :The Science of the total environment 2015
Offer Rozenstein Nurit Agam Carmine Serio Guido Masiello Sara Venafra Stephen Achal Eldon Puckrin Arnon Karnieli

Land surface emissivity (LSE) in the thermal infrared depends mainly on the ground cover and on changes in soil moisture. The LSE is a critical variable that affects the prediction accuracy of geophysical models requiring land surface temperature as an input, highlighting the need for an accurate derivation of LSE. The primary aim of this study was to test the hypothesis that diurnal changes in...

2008
O. Durán

16 In this work we present measurements of vegetation cover over parabolic dunes with 17 different degree of activation along the north-eastern Brazilian coast. We extend 18 the local values of the vegetation cover density to the whole dune by correlating 19 measurements with the relative brightness index C of high resolution QuickBird 20 panchromatic satellite image of the dune field. Next, we...

2006
Hans J. Herrmann Orencio Durán Eric J. R. Parteli Volker Schatz

Sand dunes are found in a wide variety of shapes in deserts and coasts, and also on the planet Mars. The basic mechanisms of dune formation could be incorporated into a continuum saltation model, which successfully reproduced the shape of the barchan dunes and has been also applied to calculate interaction of barchans in a field. We have recently extended our dune model to investigate other dun...

2007
Nathalie M. Vriend Melany L. Hunt Robert W. Clayton Christopher Earls Brennen Katherine S. Brantley Angel Ruiz-Angulo

[1] Desert booming can be heard after a natural slumping event or during a sand avalanche generated by humans sliding down the slip face of a large dune. The sound is remarkable because it is composed of one dominant audible frequency (70 to 105 Hz) plus several higher harmonics. This study challenges earlier reports that the dunes’ frequency is a function of average grain size by demonstrating...

1998
Zongying He Shenggong Li Yoshinobu Harazono

Horqin Sandy Land is located in northeast China (4241’-4515’N, 11835’-12330’E). The wind-sand topography in Horqin Sandy Land can be described as two series--sand deposition and wind erosion. Wind is the natural force for the formation of wind-sandy environment, under windsandy environment, the wind erosion processes such as sand drifting, dust-storm, etc. occurred frequently because of the fre...

2017
Ping Lü Clément Narteau Zhibao Dong Olivier Rozier Sylvain Courrech du Pont

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 sa...

Journal: :Physiological zoology 1997
N Corp M L Gorman J R Speakman

Interpopulation variation in the diet of the wood mouse, Apodemus sylvaticus, is well documented. In this study, we examined the gut morphology and apparent absorption efficiencies of two populations of wood mice whose diet in the field was known to differ. One population inhabited sand dunes, where food availability was relatively low and the diet was dominated by invertebrates. The other popu...

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