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Measuring & Modeling Snow

Measuring & Modeling Snow. Andrew G. Slater. SNOW!. Air to Soil Temperature Gradient. Ivotuk is in the northern foothills of the Brooks Range, AK. Integrated Extent-Duration of Snow. http://cires.colorado.edu/~aslater/NH_SNOW/. June Snow Cover Retreat. Derksen and Brown, 2012.

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Measuring & Modeling Snow

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  1. Measuring & ModelingSnow Andrew G. Slater

  2. SNOW!

  3. Air to Soil Temperature Gradient Ivotuk is in the northern foothills of the Brooks Range, AK

  4. Integrated Extent-Duration of Snow http://cires.colorado.edu/~aslater/NH_SNOW/

  5. June Snow Cover Retreat Derksen and Brown, 2012

  6. Rapid Snow Retreat in 2013

  7. Snow Extent : Observations & Models

  8. Trends in Snow Extent (1966-2012)

  9. Nth Hemisphere Snow Mass/Depth Data

  10. March SWE : Spatial Correlation (2000-2009)

  11. March SWE : Spatial Correlation (2000-2009)

  12. Arctic Basins Lena Yenesy Ob MacKenzie

  13. 2000 – 2009 : Observations

  14. 2000 – 2009 : Observations + CMIP5 Models

  15. 2030 – 2039 : CMIP5 Models

  16. 2060 – 2069 : CMIP5 Models

  17. 2090 – 2099 : CMIP5 Models

  18. Measurement Methods SNOTEL and Precipitation Gauges Snow Board Photos: A. Slater

  19. Measurement Methods Sonic Snow Depth Sensor Photos: A. Slater

  20. Measurement Methods Alter DFIR Nipher Wyoming Photos: NCAR

  21. Measurement Methods Pyranometer and Stevenson Screen Photos: A. Slater

  22. Other Data Sources CAIC Tower Berthoud Pass Snow courses & weather networks Photos: A. Slater

  23. Surface Hoar Photos: A. Slater

  24. Depth Hoar Photo: http://www.avalanche.org/

  25. Depth Hoar Formation • Driven by vapor density gradient, but temperature is a good proxy • Large temp gradient, high temperatures & large pores = big crystals • ~10°C/m is the critical gradient

  26. Fresh Snow Density Grant & Rhea, 1974 Colorado

  27. Snow Crystal Formation Based on Magono & Lee, 1966 (Observations) Nakaya, 1945 (Lab Experiments)

  28. North Slope Alaska, April 2009

  29. Constructive Metamorphism Snow stratigraphy (right) at site KD-7 (Yamba Lake). The color representation of the NIR image of the left side of the snowpit indicates the relative grain size (yellow and red = largest; purple and blue = smallest). Sturm et al., 2008

  30. 2011

  31. 2012

  32. 2013

  33. * * * * * Manabe, 1969 – 1970’s Radiation Albedo = 0.70 Snowfall Air to ground temperature gradient Snow Mass/Depth Accumulation Ablation Time

  34. Wind * * * * * Climate Model(1980’s) Radiation Turbulentfluxes Albedo ~ Age Snowfall Sublimation Evaporation Snow Mass/Depth Runoff Ground heat flux Metamorphism = f (mass) Accumulation Ablation Time

  35. Wind * * * * * Land Surface Model (1990’s) Radiation Turbulentfluxes Albedo ~ Tsnow Snowfall Sublimation Evaporation Snow Mass/Depth settling compaction compaction Runoff Metamorphism = f (age) Accumulation Ablation Time Ground heat flux

  36. Wind * ‘ ‘ * ‘ ‘ * * ‘ * More Sophisticated Snow Model (2000’s) Radiation Turbulentfluxes Heat due to rain Albedo ~ Age ~ Sun angle ~ Cloud Snowfall Sublimation Evaporation Rain Snow Mass/Depth ice layer wet metamorphism settling settling compaction compaction Runoff Metamorphism = f (mass, temperature, age) Accumulation Ablation Time Ground heat flux

  37. Instrument Pass Bands & Spectral Reflectences Image Courtesy: Bruce Raup, NSIDC

  38. Any Questions Before I Leave?

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