Seepage-induced penetration of water vapor and dust beneath ripples and dunes
Résumé
We present stratigraphic measurements of humidity and bulk density beneath the surface of a barchan dune obtained with a capacitance probe. A model shows that air seeping through the sand bed in response to spatial variations of static pressure along the ripple surface guides water vapor through ripple crests and gradually stores dust beneath troughs. The accumulated dust remains trapped beneath the relatively compact trough surface until wind is violent enough to mobilize sand deeply.