Storm wind flow over a foredune, Prince Edward Island, Canada

Near-surface airflow over a morphologically simple, vegetated 8m high foredune with a small wave cut scarp was measured during a high velocity (11-18 ms^-1), onshore, sand-transporting gale event. Flow across the foredune was characterized by topographically forced accelerations up the steep stoss slope leading to a progressive increase upslope in near-surface wind speed even within the vegetation canopy. As incident wind speed approached ∼14 ms^-1 (measured at 3m height on the crest), jet-like flow structures occurred at the foredune crest between the vegetation canopy and the 1.8m height region. Comparison of velocity profiles through time indicates that the jet structure remains consistent as velocities increase from 14 ms^-1 to 18 ms^-1. Throughout the storm period, even with a very small fetch, an echo dune formed at the scarp base. Sand in saltation bypassed the echo dune and scarp wall and was transported up the stoss slope. Fine sand was also transported in suspension across the entire dune and downwind. The long term implications for foredune development are discussed.