spectral reflectance

[7.3.3.13] ρ(λ)
ρ(λ) = Φ_rλ/Φ_iλ

The ratio of the reflected flux to the incident flux at a particular wavelength, λ, or within a small band of wavelengths, Δ λ, about λ.

Note: The various geometrical aspects of reflectance may each be considered restricted to a specific region of the spectrum and may be so designated by the addition of the adjective “spectral.”