Experimental uncertainties associated with plot-scale mass balance measurements of aeolian sediment using MWAC samplers

Modified Wilson And Cook (MWAC) sediment catchers are commonly used for qantifying aeolian sediment transport in the saltation layer. The accuracy of aeolian mass flux and mass balance estimates using MWAC catchers has, however, not been reported in detail so far. By combining analytical error propagation equations and Monte Carlo simulations, this study proposes a random error propagation scheme which incorporates 6 sources of uncertainty: sediment mass, MWAC inlet diameter, vertical position of the catchers, trapping efficiency, horizontal spacing between catcher arrays and wind direction. The relative error on the measured unit mass transport is found to range between 2 ans 20% with an average of 10%. However, the relative uncertainty on the corrected cumulative unit sediment mass transport was found to be equal to 32% on average, because of a high relative uncertainty on the trapping efficiency of 31%. The relative uncertainty on plot-scale mass balances ranged between 32 and 80%. Uncertainty on the trapping efficiency and on the measured unit mass transport contributed most to the mass balance uncertainty, but the uncertainty on wind direction sometimes also contributed substantially.