Video: Lee-side processes, Coral Pink Sand Dunes State Park, USA

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These two compilations (one with clips oriented horizontally and the other vertically) are of a slipface of a transverse dune at Coral Pink Sand Dunes State Park, Utah, USA (37.052018, -112.712365 WGS84), during strong wind (estimated at about 50 km/h) from the southwest, mostly perpendicular to the brink. It was late afternoon (around 5:30pm), with fortunate lighting at a glancing angle that accentuated surface textures on the slipface.

There are vigorous lateral eddy currents, most intense at the right-most end of the dune, possibly due to the shape of the terrain at that end. Use Google Earth/Maps for an overhead view of the shape of the dune.

Stoss slope erosion appeared to be reduced by moisture. Likely any previously sun-dried looser sand had eroded earlier in the day.

The camera was protected by a plastic bag, exposing only a lens filter mount (which had a transparent filter). Sounds of sand grains hitting the bag (grainfall) are audible during the videos.

If you've got videos of leeside activity, especially on slipfaces of high dunes (eg., Africa, Middle East, Asia), I'd love to see them.

Part One (~9 minutes): Horizontal camera orientation

Shows sand blowing over brink, uplift, leeside vortices, grainflow, avalanching.

Fig 1. Compilation of video clips and still images of slipface activity during high wind on a transverse dune at Coral Pink Sand Dunes State Park, Utah, USA (camera oriented horizontally).

Part Two (~4 minutes): Vertical camera orientation

Shows mostly grainflow (avalanches in progress).

Fig 2. Compilation of video clips and still images of slipface activity during high wind on a transverse dune at Coral Pink Sand Dunes State Park, Utah, USA (camera oriented vertically).

Related

Eastwood EN, Kocurek G, Mohrig D, Swanson T. Methodology for reconstructing wind direction, wind speed and duration of wind events from aeolian cross-strata. Journal of Geophysical Research: Earth Surface (20032012). 2012 Sep 1;117(F3).

References

Momiji H, Carretero-Gonzalez R, Bishop SR, Warren A. Simulation of the effect of wind speedup in the formation of transverse dune fields. Earth Surface Processes and Landforms. 2000 Aug 1;25(8):905-18.