Absorption: a measure of the ability of a surface to absorb incident energy, often at specific wavelengths.
Albedo: the ratio of the radiation reflected from an object to the total amount incident upon it, for a particular portion of the spectrum.
Detector index: index of the CCD detector (1 to 15).
Frame: the set of measurements acquired by the instrument at a given time.
Irradiance: the density of the radiant flux that is incident on a surface per unit of wavelength.
Instrument frame: a set of instrument pixels acquired at the same instant
Luminance: the quantitative attribute of light that correlates with the sensation of brightness and is the evaluation of radiance by means of the standard luminosity function.
Optical density: the logarithm to base 10 of the inverse of the transmittance.
Photon: a particle of light (or other electromagnetic radiation).
Pixel: Picture element: the set of measurements taken for a given location at a given time.
Product frame: a set of product pixels corresponding to a given satellite position.
Radiance: a measure of the energy radiated by the object together with the frequency distribution of that radiation.
Radiative transfer equation: the equation which describes the radiation passage through a scattering and absorbing medium.
Radiometer: an instrument for quantitatively measuring the intensity of electromagnetic radiation in some band of wavelengths in any part of the electromagnetic spectrum. Usually used with a modifier, such as an infrared radiometer or a microwave radiometer.
Rayleigh scattering: a form of atmospheric scattering that is caused when radiation interacts with particles whose diameter is much smaller than its wavelength. It therefore affects shorter wavelengths.
Reflectance: ratio of the intensity of reflected radiation to that of the incident radiation on a surface.
Rxxx: Water-leaving reflectance
Sample: single measurement item, i.e. a single spectral value of a given pixel.
Scattering: the process in which a wave or beam of particles is diffused or deflected by collisions with particles of the medium which it traverses.
Scattering phase function: the angular function which describes the directional scattering probability as a photon interacts with a scattering particle.
Spectrometer: a device used to measure radiant intensity or to determine the wavelengths of various radiations.