Spatial source contribution and interannual variation in deposition of
dust aerosols over the Chinese Loess Plateau
Abstract
The Chinese Loess Plateau (CLP) in northern China serves one of the most
prominent loess records in the world. The CLP is an extensive record of
changes in past aeolian dust activity in East Asia; however, the
interpretation of the loess records is hampered by ambiguity regarding
the origin of loess-forming dust and an incomplete understanding of the
circulation forcing dust accumulation. In this study, we used a novel
modeling approach combining a dust emission model FLEXDUST with
simulated back trajectories from FLEXPART to trace the dust back to
where it was emitted. Over 21 years (1999-2019), we modeled back
trajectories for fine (~ 2mu) and super-coarse
(~ 20mu) dust particles at six CLP sites during the peak
dust storm season from March to May. The source receptor relationship
from FLEXPART is combined with the dust emission inventory from FLEXDUST
to create site-dependent high-resolution maps of the source contribution
of deposited dust. The nearby dust-emission areas dominate the source
contribution at all sites. Wet deposition is important for dust
deposition at all sites, regardless of dust size. Non-negligible amounts
of dust from distant emission regions could be wet deposited on the CLP
following high-level tropospheric transport, with the super-coarse dust
preferentially from emission areas upwind of sloping topography. On an
interannual scale, the phase of the Arctic Oscillation (AO) in winter
was found to have a strong impact on the deposition rate on the CLP,
while the strength of the East Asian Winter Monsoon was less
influential.