Abstract
Mineral dust is among the top contributors to global aerosol loads and
is an active element in the Earth system. Ability of non-photosynthetic
vegetation (NPV) to suppress dust emission has been supported by
observations and small-scale studies, but current regional to global
scale models fail to include NPV in the vegetation coverage input. In
this study, we implemented a satellite-based total vegetation dataset,
which included NPV, into a regional atmospheric chemistry model and
conducted simulations of the entire year 2016 for the conterminous
United States. We also conducted a control simulation using only the
photosynthetic vegetation (PV) to analyze the effects of NPV on dust
emissions. Above 10% decreases in simulated dust emissions are seen
over most of the southwestern United States from spring to autumn due to
NPV. Reductions in dust concentrations are the largest in spring, and
when compared to observations, attenuate the overpredictions of fine
soil concentrations at over 93% of the observation sites in the western
U.S. Further analyses of essential parameters to the inclusion of NPV
indicate that sheltering the surface and increasing the threshold
velocity through drag partitioning are major mechanisms for the
suppression of dust emissions. On the other hand, NPV causes the
friction velocity to increase by more than 10% over most erodible lands
during autumn and winter, which can amplify the dust flux. This study
highlights the necessity of including NPV into the dust model and states
that uncertainty analyses of total vegetation datasets are important.