Eolian Suspension Above the Saltation Layer, the Concentration Profile

ABSTRACT The acquisition of a new set of data on dust emission obtained at Owens Lake, California, was used to assess the performance of a previously published theoretical model that describes the normalized concentration profile of material in suspension above an actively emitting surface as a logarithmic function. The normalized concentration profile has more commonly been modeled as a power law. Least-squares regression was used to fit both the logarithmic and the power-law model to approximately 20 hours of data on 10-minute average concentration profiles. Results for all these data combined and for each individual profile indicated that the logarithmic model better explains the concentration gradient profile than the power-law model. The predicted behavior of the model parameters, including a concentration scaling parameter * and a transfer coefficient for suspended particles , was examined. It was observed that * divided by a defined reference concentration was relatively invariant during emission events as predicted by the model and had a value of 0.18 (± 0.02). For the reference heights at which particle concentration and wind speed were measured (1.7 and 9 m) the transfer coefficient for suspended particles was approximately 0.22 (± 0.05) of the calculated momentum transfer coefficient defined here as the wind speed at the reference height divided by the friction velocity.

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