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The Color Colour of Snow and its Interpretation from Imaging Spectrometry

The Color Colour of Snow and its Interpretation from Imaging Spectrometry. Spectral reflectance of clean snow. Snow is a collection of scattering grains. Snow spectral reflectance and absorption coefficient of ice. Snow/cloud discrimination with Landsat. Bands 3 2 1 (red, green, blue).

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The Color Colour of Snow and its Interpretation from Imaging Spectrometry

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  1. The ColorColour of Snow and its Interpretation from Imaging Spectrometry

  2. Spectral reflectance of clean snow

  3. Snow is a collection of scattering grains

  4. Snow spectral reflectance and absorption coefficient of ice

  5. Snow/cloud discrimination with Landsat Bands 3 2 1 (red, green, blue) Bands 5 4 2

  6. Spectral solar irradiance

  7. Net solar radiation

  8. Analyses of snow properties from imaging spectrometry • Spectral albedo and conversion to broadband albedo • [Nolin & Dozier, Remote Sens. Environ., 2000] • Fractional (subpixel) snow-covered area, along with albedo • [Painter et al., Remote Sens. Environ., 2003] • Liquid water in surface layer • [Green et al., Water Resour. Res., 2006] • Absorbing impurities • [Painter et al., Appl. Environ. Microbiol., 2001; Geophys. Res. Lett., 2007]

  9. Conventional approach to estimating albedo Satellite radiance (~5% error) Surface reflectance (>5%) Narrowband albedo (5-10%) Broadband albedo (5-10%)

  10. Estimate grain size from the1.03mm absorption feature

  11. Measured vs remotely sensed grain size ETH/CU Camp12 June 2001q=46.6° 500 550 600

  12. Spectral mixture analysis

  13. Snow-covered area in the Tokopah Basin (Kaweah River drainage), Sierra Nevada AVIRIS 21 May 1997 05 May 1997 18 June 1997 20 km

  14. Grain size in the Tokopah Basin (Kaweah River drainage), Sierra Nevada 21 May 1997 05 May 1997 18 June 1997 20 km

  15. Absorption by three phases of water

  16. Wet snow (Green et al, WRR, forthcoming)

  17. Surface wetness with AVIRIS, Mt. Rainier,14 June 1996 AVIRIS image, 409, 1324, 2269 nm precipitable water, 1-8 mm liquid water, 0-5 mm path absorption vapor, liquid, ice (BGR)

  18. Progression of snow wetness throughout morning Surfacewetness09:54 am N AVIRIS20 May 1996 Surfacewetness11:32 am 70 km

  19. Dust and algae

  20. Spectral reflectance of dirty snow and snow with red algae (Chlamydomonasnivalis)

  21. Radiative forcing concept

  22. Radiative forcing by dust in snow

  23. Applications: snowmelt modeling,Marble Fork of the Kaweah River Snow Covered Area net radiation> 0 degree days > 0 where: mq= Energy to water depth conversion, 0.026 cm W-1 m2 day-1 ar= Convection parameter, based on wind speed, temperature, humidity, and roughness

  24. Magnitude of snowmelt: Modeled – Observed snow water equivalent AVIRISalbedo SWE difference, cm Tokopah basin, Sierra Nevada assumed w/ update assumedalbedo

  25. Acknowledgments • Steve Warren & Warren Wiscombe • Model for the spectral albedo of snow (1980) • NASA • Funding on remote sensing of snow since 1977 • UC Santa Barbara • Great place to think about snow and ice • Former and current students on this topic • Bert Davis, Rob Green, Danny Marks, Anne Nolin, Tom Painter, Karl Rittger, Walter Rosenthal, Jiancheng Shi

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