October 2006: The Impact of Transpacific Transport
of Mineral Dust in the United States

We used the GEOS-Chem model to estimate the impact of transpacific transport of mineral dust on aerosol concentrations in North America during 2001. The model captures the magnitude and seasonal cycle of surface dust concentrations in the Northern Pacific, the free tropospheric outflow of dust from Asia during the TRACE-P and ACE-Asia campaigns, and the timing and distribution of Asian dust outbreaks over the United States in April-May 2001. Beyond these outbreaks we find a persistent presence of Asian dust over North America in spring, summer and fall. We find that in western states during 2001 transpacific sources accounted for 40% of the 20% worst visibility days for which dust was the principal aerosol component (worst dust days).

The figure shows the simulated overseas contribution (%) to dust extinction for the 20% worst visibility days for which dust was the principal aerosol component (worst dust days), together with the number of model worst dust days in 2001 attributed to transpacific transport.

For a complete description see Fairlie et al. [2006].