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Dust cover speeds up snowmelt

Jul 05, 2007 / alpMedia
A new study reveals that dust blown hundreds of kilometres by the wind from erosion zones or dry regions is capable of speeding up the snowmelt in the mountains of Colorado/USA by around one month. Researchers at the National Snow and Ice Data Center in Boulder were surprised not by the fact that the dust-covered snow cover was found to melt more quickly but by the extent to which this occurred in measurements and simulations.
The darker dust absorbs more heat than the bright, reflecting snow cover, thereby forcing the snowmelt. The more the climate heats up, the less snowfall is expected and the more seldom the dust layers are likely to be covered by snow. This in turn serves to accelerate the whole phenomenon further. In the southwest US in particular the climate is becoming hotter and drier, which further promotes disturbed desert dust. The same mechanism is at work in principle in the Himalayas and the Alps (e.g. with the emission of Sahara dust). The study was published on 23 June in the Geophysical Research Letters (Vol. 34, No. 12): www.agu.org/pubs/crossref/2007/2007GL030284 (en)