『Abstract
We simulated the global transport of dust emitted from all major
dust source regions on earth by using a global three-dimensional
chemical transport model for the year 2000. A modified dust emission
flux scheme and an advanced nonlocal diffusion scheme for accurately
determining the atmospheric eddy diffusivity in the atmospheric
boundary layer were implemented to improve the chemical transport
model. We specifically examined and analyzed dust storms that
occurred in China and northern Africa. Four scenarios representing
the global transport of dust from dust storms originating in the
Loess region and the Gobi, Takla Makan, and Sahara deserts, respectively,
were simulated. The results of each scenario were then compared
with those resulting from all major dust source regions on earth,
to identify which deserts have a major impact on dust transport
and its deposition in Japan. The dust from the Sahara desert,
most from the western part that was found in this study, reached
Japan in 9-10 days, while Gobi and Loess region dust took 2 to
3 days, and 4 days for Takla Makan dust. The model-calculated
monthly total deposition of dust mass from all major dust source
regions was compared with comprehensive measurements of total
deposition collected at sampling stations distributed over Japan,
and good agreement was generally found. From these analyses, it
was also indicated that dust emitted from other deserts, including
the Turkestan, Iranian, and Arabian, could have a significant
impact on dust deposition on Japan.
Keywords: atmospheric transport; Asian dust; Sahara dust; global
model simulation; dust storms; dust depositions』
1. Introduction
2. Description of the model
2.1. Turbulent diffusion in the atmospheric boundary layer
2.2. Atmospheric surface eddy fluxes
2.3. Wet and dry deposition processes
2.4. Dust emission flux
3. Brief description of total deposition measurement
4. Model results
5. Uncertainties and sensitivities
6. Summary and conclusions
Acknowledgments
References