Observations of Aeolian Ripple migration on an Egyptian Seif Dune using an Inexpensive Digital Timelapse Camera

I report experiments on the observation of sand ripples on the Quattani dunes in Egypt using an inexpensive ($150) digital timelapse camera. Simple ripples in the fine sand had a wavelength of 10cm and propagated downwind (windspeed ~10m/s) at a speed of ~3cm/minute, and Y-junction defects moved one wavelength forward in the propagating ripple pattern over ~6 minutes. This defect propagation speed of ~0.5 times the ripple speed is rather slower than suggested in idealized models . Compound ripples at a nearby site were also observed the megaripples moved at ~0.2 cm/minute while smaller superposed normal ripples moved ~3-4x faster: the small ripples did not propagate through the larger ones. Experimental technique and some aspects of the design of a windsock/gnomon for use in further studies are discussed. A similar experimental setup should be able to observe fastmoving barchans.