Aeolian mass flux characterization: uncertainties from a wind-tunnel perspective and implications for field studies

Aeolian sediment traps are widely used to estimate the total volume of wind-driven sediment transport, but also to study the vertical mass distribution of a saltating sand cloud. The reliability of sediment flux estimations from this data are dependent upon the specific configuration of the measurement compartments and the analysis approach used. In this study, we analyse the uncertainty of these measurements by investigating the vertical cumulative probability distribution and relative sediment flux derived from both wind-tunnel and field studies. Three existing datasets were used in combination with a newly acquired meteorological dataset, which was collected in combination with sediment fluxes from six different events, using three customized catchers at one of the beaches of Ameland in the north of The Netherlands. Fast-temporal data collected in a wind-tunnel shows that eq has a scattered pattern between impact and fluid threshold, but increases linearly with shear velocities above the fluid threshold. For finer sediment fractions, a larger portion of the sediment was transported closer to the surface compared to coarser sediment fractions. It was also shown that errors originating from the the distribution of the sampling compartments, specifically the location of the lowest sediment trap relative to the surface, can be identified using the relative sediment flux. In the field, surface conditions such as surface moisture, surface crusts or frozen surfaces have a more pronounced, but localized effect, than shear velocity. Uncertainty in aeolian mass flux estimates can be reduced by placing multiple compartments in closer proximity to the surface.