Where Deserts and Mountains Collide The Implications of Accelerated Snowmelt by Disturbed Desert Dust Thomas H. Painter Snow Optics Laboratory University.

Where Deserts and Mountains Collide

The Implications of Accelerated Snowmelt

by Disturbed Desert Dust Thomas H. PainterSnow Optics LaboratoryUniversity of Utah

Snowmelt and Water• 75% of freshwater comes

from snow in the Western US

• Mountain snowpack provides enormous, critical reservoir capacity

• Early snowmelt increases growing season length, evapotranspiration, and temperatures

• Rate of snowmelt controls water management and yield

Photo: Chris Landry, Center for Snow and Avalanche Studies

Reflectivity = 72%

Absorption = 28%

Reflectivity =43%

Absorption = 57%

Snow Albedo

Reflect

ivit

y

Impact of Dust: A Perfect Storm

Dust is well timed

Dust is well placed

Dust is, well, darker than snow

April 2009 May 2009

Changes in Dust Loading

Post-disturbance

~ 1850 AD

Pre-disturbance

From Neff et al (2008), Nature GeosciencesFrom lake sediments in the Colorado Rockies

Present

Photo: McKenzie Skiles, Snow Optics Laboratory

Phoenix 2006

Future Dust Loading

albedo = 0.72

Before disturbance

albedo = 0.43

After disturbance

Snowmelt Modeling

Senator Beck Basin Study Area, Colorado, 2006

Snow

wate

r equiv

ale

nt

(mm

)

Cleaner (before disturbance)Dirtier (after disturbance )

Informing Water Managers

Colorado River Basin

May 6, 2009

MODIS-DRFS

Daily

sun

light a

bso

rbed b

y d

ust

(W/m

2)

Water in the Colorado River Basin

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