AGU: Geophysical Research Letters

 

Editors' Highlight

Dust deposition from disturbed deserts reduces mountain snow cover duration

Dust, when deposited on snow and ice, can enhance absorbed solar radiation and melt rates. To quantify these rates, Painter et al. (2007) studied Colorado's seasonally snow covered San Juan Mountains, a region containing headwaters of the Colorado and Rio Grande rivers. Using data they collected on dust deposition to mountain snow and snow energy balance from the past 3 years, they found with a coupled radiative forcing/snowmelt model that dust deposition at high elevations shortens snow cover duration by 18–35 days. In particular, a difference in recent deposition from the Colorado Plateau from four events in 2005 to eight events in 2006 led to a further doubling of radiative forcing by dust and greater melt rates. Because continued agriculture and other soil disturbances in arid regions can enhance dust emission, the authors suggested that the current duration of snow cover represents a dramatic change from that before widespread land-use changes in the late 1800s, and that projected increases in drought intensity in the U.S. desert southwest may further alter mountain snowmelt and snow cover duration.

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