  The mesoscale structure of aeolian sand transport determines a variety of
natural phenomena studied in planetary and Earth science. We analyze it
theoretically beyond the mean-field level, based on the grain-scale transport
kinetics and splash statistics. A coarse-grained analytical model is proposed
and verified by numerical simulations resolving individual grain trajectories.
The predicted height-resolved sand flux and other important characteristics of
the aeolian transport layer agree remarkably well with a comprehensive
compilation of field and wind tunnel data, suggesting that the model robustly
captures the essential mesoscale physics. By comparing the saturation length
with field data for the minimum sand-dune size, we can reconcile conflicting
previous models for this most enigmatic emergent aeolian scale and elucidate
the importance of intermittent turbulent wind fluctuations for field
measurements.
