Abstract
Aircraft measurement campaigns have revealed that super coarse dust
(diameter > 10 um) surprisingly accounts for approximately
a quarter of aerosols by mass in the atmosphere. However, most global
aerosol models either underestimate or do not include super coarse dust
abundance. To address this problem, we use brittle fragmentation theory
to develop a parameterization for the emitted dust size distribution
that includes emission of super coarse dust. We implement this
parameterization in the Community Earth System Model (CESM) and find
that it brings the model in good agreement with measurements of super
coarse dust close to dust source regions. However, the model still
underestimates super coarse dust in dust outflow regions. Thus, we
conclude that model underestimation of super coarse atmospheric dust is
in part due to the underestimation of super coarse dust emission and
likely in part due to errors in deposition processes.