What is water-leaving reflectance?
What is water-leaving reflectance?
Reflectance does not propagate through space and it cannot leave a surface, so it does not make sense to speak of the “water-leaving reflectance.” However, the term “water-leaving reflectance” is well established shorthand for “reflectance based on the water-leaving radiance and the incident irradiance,” and we will use …
What is water-leaving radiance?
Water-leaving radiance (Lw), which is defined as the upwelling radiance from the sea to the air is a fundamental parameter for ocean-color remote sensing, since its spectrum provides infor- mations on the sea-surface layer, such as chlorophylla concentration [1].
What is remote sensing reflectance?
Definition. Remote Sensing Reflectance, Rrs(λ; sr-1), is water-leaving radiance, Lw(λ), corrected for bidirectional effects of the air-sea interface and sub-surface light field, and normalized by downwelling solar irradiance, Ed(λ), just above the sea surface.
Why is surface reflectance important?
The angular distribution of the light reflected by the Earth’s surface influences top-of-atmosphere (TOA) reflectance values. This surface reflectance anisotropy has implications for UV/Vis satellite retrievals of albedo, clouds, and trace gases such as nitrogen dioxide (NO2).
What is spectral reflectance?
The spectral reflectance is the reflectance measured at a given Ts and λ, within a small wavelength interval, Δλ, centered at λ [7]. Spectral reflectance is typically named monochromatic reflectance and may be specular, diffuse, or hemispherical.
How do you calculate reflectance?
Calculate reflectance from the reflectivity. Reflectance is the square of the reflectivity so q(y) = (Gr(y)/Gi(y))^2. where q is the reflectance, y is the wavelength of the light, Gr is the reflected radiation and Gi is the incident radiation.
What does surface reflectance mean?
Surface reflectance is the amount of light reflected by the surface of the Earth. It is a ratio of surface radiance to surface irradiance, and as such is unitless, with values between 0 and 1.
What is the difference between albedo and reflectance?
Albedo is the percentage of solar energy striking a surface that is reflected away from the earth. Surface Reflectance is ratio of the amount light not absorbed by a surface to the amount of light striking the surface. Albedo is a measure of energy and Surface Reflectance is a property of a material.
Why does turbid water have higher reflectance?
The turbid water reflectance spectrum exhibits higher values than clear water in the near-infrared region and approaches zero at longer wavelengths [44] . This is due to the concentration of solutes, sediments and organic matter, whose presence reinforces the reflection in the near-infrared band. …
How does reflectance spectroscopy work?
Reflectance spectroscopy is the study of light as a function of wavelength that has been reflected from a solid, liquid, or gas (13). Thus, even though a solid crystalline structure can affect the shape of spectral features, non-crystalline materials, like glass, still display absorption features in their spectra.