RELATIONSHIPS BETWEEN THE DUST CONCENTRATIONS OVER EASTERN ASIA AND THE REMOTE NORTH PACIFIC

Dust storm reports as well as chemical data indicate that 1988 and 1989 were high-dust and low-dust years in eastern Asia, respectively. This pattern was not reflected in data from Midway, a remote island in the North Pacific, where the mineral aerosol concentrations during 1989 were as high as or higher than any year for which data are available. Analyses of meteorological data showed that the amount of precipitation, the strength of the westerly winds, and the position of large-scale meteorological features were related to the dust concentrations over eastern Asia. The observed disparity in the interannual trend in dust concentrations over Beijing and Midway was explained by differences in the source regions for the dust. Dust over eastern Asia evidently originates from source regions to the northeast of the Tibetan Plateau, while dust at Midway is ascribed to dust materials transported from the desert lands in western China. The Asian dust flux to the open ocean is influenced not only by conditions in or near the source regions but also by the large-scale atmospheric circulation patterns.