Scaling of Dust Flux With Friction Velocity: Time Resolution Effects

The intermittency of aeolian soil erosion has motivated studies to extend to small time resolution (less than 15–30 min) the scaling property of erosion fluxes with the friction velocity . However, common methods used to estimate such as the law of the wall or the eddy covariance are only valid for stationary conditions, that is, long periods of 15–30 min. Unlike these methods, the wavelet transform method is applicable for nonstationary conditions. Here, this method is used to investigate the scaling property of the dust flux with at 1‐min and 10‐s resolutions, during erosion events. At 15‐min resolution, and estimated from the wavelet transform are identical to those obtained by eddy covariance. At smaller resolution, and exhibit strong fluctuations around their 15‐min trend, reflecting the nonstationarity of the flow and the intermittency of dust emission, respectively. While the 15‐min resolution appears as correlated with as with the mean wind speed , with decreasing resolution, becomes less correlated with but still significantly correlated with . Our results suggest that is a suitable scaling parameter of over usual 15‐ to 30‐min periods with the advantage of being height independent compared to . However, at small time resolution, becomes more relevant to scale , the surface friction velocity becoming hardly accessible due to the absence of a constant momentum flux layer. Our study demonstrates the suitability of the wavelet transform to estimate dust fluxes at small time resolution or during nonstationary events.