Indian Smoke Signals

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Science  31 Aug 2001:
Vol. 293, Issue 5535, pp. 1559
DOI: 10.1126/science.293.5535.1559c

Recently, high concentrations of anthropogenic pollution from south and southeast Asia have been found over large regions of the northern Indian Ocean. This has raised the question as to whether the region's cloud properties have been influenced by increasing aerosols. Results from models indicate that solar absorption by soot aerosols can decrease daytime cloud cover.

Norris has tested whether this effect may be important over the Indian Ocean, by examining changes in cloudiness between 1952 and 1996, a period during which there have been large increases in Asian air pollution. Cloud cover actually increased over the period, as did cloud cover in the relatively clean air over the southern Indian Ocean. The similarity of these trends suggests that changes in cloudiness in the northern Indian Ocean are not the result of increased soot pollution and that other factors, such as variations in sea surface temperatures, must be responsible. — HJS

Geophys. Res. Lett. 28, 3271 (2001).

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