  Aeolian transport of sand and dust is driven by turbulent winds that
fluctuate over a broad range of temporal and spatial scales. However, commonly
used aeolian transport models do not explicitly account for such fluctuations,
likely contributing to substantial discrepancies between models and
measurements. Underlying this problem is the absence of accurate sand flux
measurements at the short time scales at which wind speed fluctuates. Here, we
draw on extensive field measurements of aeolian saltation to develop a
methodology for generating high-frequency (25 Hz) time series of total
(vertically-integrated) saltation flux, namely by calibrating high-frequency
(HF) particle counts to low-frequency (LF) flux measurements. The methodology
follows four steps: (1) fit exponential curves to vertical profiles of
saltation flux from LF saltation traps, (2) determine empirical calibration
factors through comparison of LF exponential fits to HF number counts over
concurrent time intervals, (3) apply these calibration factors to subsamples of
the saltation count time series to obtain HF height-specific saltation fluxes,
and (4) aggregate the calibrated HF height-specific saltation fluxes into
estimates of total saltation fluxes. When coupled to high-frequency
measurements of wind velocity, this methodology offers new opportunities for
understanding how aeolian saltation dynamics respond to variability in driving
winds over time scales from tens of milliseconds to days.
