Eolian dust from the lower atmosphere of the eastern Atlantic and Indian Oceans, China Sea and Sea of Japan

Abstract

Dust-loadings in the lower atmosphere of the Atlantic and Indian Oceans and the China Sea and Sea of Japan are given. Average dust-loadings decrease in the following order: North Atlantic (northeast trades, ∼ 7.7 μg/m 3 of air) > northern Indian Ocean (∼ 1.2 μg/m 3 of air) > South Atlantic (southeast trades, ∼ 0.78 μg/m 3 of air) = southern Indian Ocean (∼ 0.68 μg/m 3 of air) > China Sea (∼ 0.21 μg/m 3 of air). There are differences in the clay mineralogies of dusts transported in similar latitudes in the North Atlantic and northern Indian Oceans. Dusts in the Atlantic northeast trades are dominated by kaolinite from the soils of equatorial Africa; dusts in the northeast monsoons of the northern Indian Ocean have a source in the arid regions of the Rajasthan desert where illite is the principal clay mineral. In the regions investigated quartz occurs in larger amounts in the dusts of the Northern Hemisphere (∼ 7% quartz) than those of the Southern Hemisphere (∼ 3% quartz) over both the Atlantic and Indian Oceans. From the results given in the present paper and those reported in the literature a map is presented illustrating the order of magnitude of lower atmospheric dust-loadings in part of the world ocean.