Unsteady aeolian saltation.

Wind velocity and saltating grain count rate in the natural unsteady aeolian sediment transport are synchronously measured on the gently inclined windward slope of one horn of a large barchan. The obtained time series of these two variables are analyzed, by using the improved complete ensemble empirical mode decomposition and wavelet coherence, to investigate the wind-saltation interactions at different timescales. It is found that the wind-saltation trend relation obeys the traditional low-order polynomial expressions, and saltation mode is roughly proportional to its corresponding wind mode if they are strongly correlated. As a conclusion, it is probable to partly predict instantaneous saltation activities near the surface by the empirical trend and effective modes of wind speed at a given height.