09-RemoteSensing

09-RemoteSensing - Applications Energy balance calculations...

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3/26/2008 1 Remote Sensing of Alpine Snow ESM 236 2 Different concepts in different parts of spectrum Visible, near-infrared, and infrared • Independent scattering Weak polarization Microwave and millimeter wave • Extinction per unit volume • Polarized signal 3 – Scalar radiative transfer • Penetration near surface only – ~½ m in blue, few mm in NIR and IR • Small dielectric contrast between ice and water – Vector radiative transfer • Large penetration in dry snow, many m – Effects of microstructure and stratigraphy – Small penetration in wet snow • Large dielectric contrast between ice and water Applications • Energy balance calculations • Remote sensing (inversion of properties (inversion of properties from signal) N=n+ik, Index of refraction (complex) θ i θ r I 0 I dx 5 0 sin sin i r c n c θ == 4 0 4 kx dI k I dx I e I π λ =− = Optical properties of ice — visible and near-infrared wavelengths refractive index (real) 1.30 1.32 1.34 refractive index (imag) 1.0E-4 1.0E-3 1.0E-2 e-folding distance, m 1 10 100 ice water 6 1.16 1.18 1.20 1.22 1.24 1.26 1.28 0.4 0.8 1.2 1.6 2.0 2.4 ice water 1.0E-10 1.0E-9 1.0E-8 1.0E-7 1.0E-6 1.0E-5 ice water 0.00001 0.0001 0.001 0.01 0.1 wavelength, μ m (Warren, Applied Optics, 1982)
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3/26/2008 2 Basic scattering properties of a single grain • Mie theory, based on N and x=2 π r/ λ ϖ —s ing le- scattering albedo 7 g — asymmetry parameter Q ext extinction efficiency 0 3( ) 4 ext ice SWE Q r τ ρ = Multiple scattering in snow 8 Snow spectral reflectance and absorption coefficient of ice reflectance 0.7 0.8 0.9 1.0 absorption coefficient 1.0E-04 1.0E-03 1.0E-02 9 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 wavelength, um 1.0 mm 1.0E-09 1.0E-08 1.0E-07 1.0E-06 1.0E-05 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 wavelength, um Snow/cloud discrimination 0.6 0.8 1 nce 10 0 0.2 0.4 00 . 511 . 522 . 5 wavelength, μ m reflecta snow water cloud ice cloud Landsat Thematic Mapper (TM) 30 m spatial resolution 185 km FOV 11 Spectral resolution 1. 0.45-0.52 μ m 2. 0.52-0.60 μ m 3. 0.63-0.69 μ m 4. 0.76-0.90 μ m 5. 1.55-1.75 μ m 6. 10.4-12.5 μ m 7. 2.08-2.35 μ m 16 day repeat pass Snow properties from remote sensing in VIS, NIR, SWIR variable accuracy time (d) remarks Extent 10% 7 mixed pixels Albedo 0.02 15 infer from properties Surface wetness 50% 7 feasible Grain size 50% 15 to infer albedo
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This note was uploaded on 08/06/2008 for the course ESM 236 taught by Professor Dozier during the Spring '08 term at UCSB.

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09-RemoteSensing - Applications Energy balance calculations...

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