Dust on snow controls springtime river rise in the West

A new study has found that dust, not spring warmth, controls the pace of spring snowmelt that feeds the headwaters of the Colorado River. Contrary to conventional wisdom, the amount of dust on the mountain snowpack controls how fast the Colorado Basin’s rivers rise in the spring regardless of air temperature, with more dust correlated with faster spring runoff and higher peak flows.

The finding is valuable for western water managers and advances our understanding of how freshwater resources, in the form of snow and ice, will respond to warming temperatures in the future. By improving knowledge of what controls the melting of snow, it improves understanding of the controls on how much solar heat Earth reflects back into space and how much it absorbs—an important factor in studies of weather and climate.

“The faster the snow melts and the rivers rise, the more nimble water managers need to be in making their allocations,” said Jeff Deems, a co-author of the new study and scientist at the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder. “A faster rise means less time and more uncertainty in making these critical decisions, increasing the risk of error.”

When snow gets covered by a layer of windblown dust or soot, the dark topcoat increases the amount of heat the snow absorbs from sunlight. Lead author Tom Painter of the NASA Jet Propulsion Laboratory in Pasadena, California, has been researching the consequences of dust on snowmelt worldwide. This is the first study to focus on which has a stronger influence on spring runoff: warmer air temperatures or a coating of dust on the snow.

See the NASA news release here.

Media contacts
Natasha Vizcarra and Agnieszka Gautier
National Snow and Ice Data Center, University of Colorado Boulder
press@nsidc.org, +1 303-492-1497