The effect of mid-air collisions on aeolian saltation is investigated
using concentration profiles and grain velocities predicted by a numer
ical saltation model. The probability of a mid-air collision is found
to be greater at high wind speeds. It is also found that mid-air colli
sions tend to reduce the number of grain/bed impacts and thus reduce t
he number of ejecta near the bed; this, in turn, reduces the intensity
of mid-air collisions. It is suggested that this feed-back mechanism
significantly influences transport rates at high wind speeds.