Climate Fact: Taklimakan Desert Dust
Dust in the atmosphere works to reflect incoming (shortwave) radiation, working to cool the Earth, and it also absorbs outgoing (longwave) radiation, which works to warm the planet. Each of the world’s major crustal dust sources (such as the Gobi, the Sahara Desert, and the Lake Chad Basin) have distinct “signatures” composed of relative concentrations of elements such as iron, calcium, magnesium, etc. contained in the dust. As such, these different dust sources will have different reflective and absorptive properties and their respective impacts on the climate will vary. Analysis of how atmospheric dust originating in the Taklimakan Desert in China interacts with incoming and outgoing solar energy reveals that the dust has an overall cooling effect over the parts of the world it blows over. Specifically, while the dust absorbs about 28.4 Watts worth of outgoing longwave radiation for every square meter it covers it also reflects about 48.1 Watts worth of shortwave energy. The warming cancels out about 58 percent of the cooling effect. The effects of the dust are not confined to Central Asia. Much of the atmospheric dust that covers the Pacific Northwest in the spring (following the peak season of upper atmospheric flow from Central Asia over the Pacific) comes from the Taklimakan Desert.
Season: Spring
Sources: Fischer, EV et al. “A decade of dust: Asian dust and springtime aerosol load in the U.S. Pacific Northwest.” Geophysical Research Letters 36 (2009): L03821 and Xia, X and Zong, X. “Shortwave versus longwave direct radiative forcing by Taklimakan dust aerosols.” Geophysical Research Letters 36 (2009): L07803.)
