Trans-Pacific yellow sand transport observed in April 1998: A numerical simulation

A yellow sand transport episode from the Asian continent to Japan and North America which occurred in April 1998 is simulated. A new on-line dust trac er model coupled with a regional-scale meteorological model is developed an d applied to this dust storm episode. The results for two large dust events that started during April 14-15 and 19-20, 1998, have been analyzed and di scussed. The first dust storm was trapped in a cutoff vortex developed over the China plain. A modeled 3-D structure of dust associated with this cuto ff vortex agreed with an observed time-height cross section of dust concent ration. Results show that the strong subsidence at the backside of the vort ex restricted the dust layer below 3 km level. Model analysis revealed that the second dust event that started during April 19-20 over inland China wa s the origin of a dust episode reported over North America. The trans-Pacif ic dust transport simulation successfully showed the dust onset near the We st Coast of North America. Elevation of the dust layer during the long-rang e transport was below 3 km. The model is extended to include the transport of an Asian origin anthropogenic tracer over the North Pacific Rim. Both th e natural-origin mineral dust and the Asian-origin anthropogenic tracer are simultaneously transported even if their emission regions are different.