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Vegetation Radiative Transfer Modelling (Nadine Gobron) - PEER

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Asymmetry factor for scattering processes<br />

•We have for isotropic medium:<br />

P<br />

↑↓ = P ↓↑<br />

•The asymmetry factor g is a single number, defined as the<br />

mean cosine of the scattering angle (-1 or +1 in our case):<br />

↓↓<br />

↓↑<br />

g<br />

= ( + 1)P + ( −1)<br />

P<br />

•Typically: g = +1 for strict downward scattering,<br />

g=-1 for strict upward scattering and,<br />

g=0 for isotropic scattering.<br />

•For the above set of equations, we have:<br />

P<br />

↑↓<br />

P<br />

↓↓ = P ↑↑<br />

↑↑ ↓↑ ↓↓<br />

+ P = P + P = 1<br />

P<br />

↑↓ = P<br />

↓↑ = (1 − g) / 2<br />

P ↑↑ = P<br />

↓↓ = (1 + g) / 2<br />

15

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