  The size distribution of mineral dust aerosols partially determines their
interactions with clouds, radiation, ecosystems, and other components of the
Earth system. Several theoretical models predict that the dust size
distribution depends on the wind speed at emission, with larger wind speeds
predicted to produce smaller aerosols. The present study investigates this
prediction using a compilation of published measurements of the size-resolved
vertical dust flux emitted by eroding soils. Surprisingly, these measurements
indicate that the size distribution of naturally emitted dust aerosols is
independent of the wind speed. The recently formulated brittle fragmentation
theory of dust emission is consistent with this finding, whereas other
theoretical dust emission models are not. The independence of the emitted dust
size distribution with wind speed simplifies both the interpretation of
geological records of dust deposition and the parameterization of dust emission
in atmospheric circulation models.
