1. Colorado Plateau Is Desertification in the Southwest Affecting the Colorado Snowpack? Chris Landry CSAS – Silverton Tom Painter, Andy Barrett NSIDC Jason Neff CU Geosciences

2. March 25, 2006 near Shiprock Desert Dust Emission Possible sources: ‘natural’ processes drought dryland farming recreation overgrazing

3. Dust Deposition in Colorado Mtns. 1999 2004 2003 March 31, 1999

4. Trajectory Analyses NOAA Hysplit Model 48 hour back-trajectories

5. Dugout Ranch Wind Speed

6. Radiative effects of desert dust deposits in alpine snow TH Painter 1, C Landry 2, J Neff 3, AP Barrett 1 1 National Snow and Ice Data Center, 2 Center for Snow and Avalanche Studies, 3 CU-Boulder, Dept of Geological Sciences CSAS Collaborative Research funded by the National Science Foundation Atmospheric Sciences, Geography, and Hydrologic Sciences Grants #ATM-0432327 to NSIDC and ATM-0431955 to the CSAS

7. Study Site – Senator Beck Basin Operated by Center for Snow and Avalanche Studies, Silverton, CO

8. May 21, 2004 Photo courtesy JPL (Ian McCubbin)

9. Swamp Angel Study Plot 11,050’ Senator Beck Study Plot 12,200’

10. Measurements Snowpack: depth, SWE (density), stratigraphy, grain size & type, temperature, wetness, coverage Climatology: air temp, RH, wind speed & direction, precipitation, pressure, dust event trajectories Radiation: incoming LW, SW; reflected SW; IR ‘skin’ temperature, snow surface albedo Sediment & Dust: mineralogy, concentrations Hydrological: temperature, EC, streamflow

11. Albedo Measurement

12. Snow Albedo   0.78 126 w/m2   0.60 224 w/m2 April 4, 2003 - San Juan Mountains

13. Snow Pits

14. May 2004 May 2005

15. Observed Snowmelt Swamp Angel Study Plot, Red Mountain Pass, CO 15 inches SWE May 20, 2003 0 inches SWE May 28, 2003

16. May 24, 2006

17. June 4, 2006

18. May 17, 2005

19. May 27, 2005

20. Spectral albedoSWESnowmelt flux

23. Preliminary Findings … Dust deposition appears to significantly decrease snow albedo on a regional scale... The ‘doubling’ of absorbed solar radiation appears to increase snowmelt rates and likely results in a higher amplitude and shorter duration snowmelt hydrograph …

24. Next Steps … Formalize findings on albedo effects... Develop modeling of ‘dust-on-snow’ effects on basin- scale snowmelt timing, intensity, and duration …