Atmospheric input of mineral dust to the western North Pacific region based on direct measurements and a regional chemical transport model

The spatial and temporal variation of the mineral aerosol concentration and its total deposition flux over the western North Pacific region were analyzed with a regional chemical transport model (AQPMS) for the period March 1994 through May 1995. Dry deposition accounted for more than 60% of the total deposition of Asian mineral dust throughout the period. The annual deposition flux was found to decrease rapidly from the coastal area (21 g m^-2 yr^-1) to the open ocean (0.8 g m^-2 yr^-1) over the study region. Sporadic dust deposition events over the HNLC region may increase the dissolved iron concentration in seawater and hence stimulate marine biological activity. The main eastward flow of mineral dust is located in the free troposphere between 30 and 40°N, above the layer of maximum concentration. These results support the intercontinental transport of Asian mineral dust across the North Pacific as background aerosol.