Reference Measurements (RM)
RM Name GBOV Acronym Units Description
RM-01 Upward shortwave irradiance SW_IN W.m-2 Upwelling radiation is radiation from below. “Shortwave” means shortwave radiation, typically understood as radiation in the spectral range between ca. 0.4 µm and 4.0 µm (==> shortwave radiation). A radiative flux is identical with the quantity measured by a cosine-collector light-meter. In accordance with common usage in geophysical disciplines, “flux” implies per unit area.
RM-01 Downward total shortwave irradiance SW_OUT W.m-2 Downwelling radiation is radiation from above. “Shortwave” means shortwave radiation, typically understood as radiation in the spectral range between ca. 0.4 µm and 4.0 µm (==> shortwave radiation). A radiative flux is identical with the quantity measured by a cosine-collector light-meter. In accordance with common usage in geophysical disciplines, “flux” implies per unit area.
RM-01 Downward diffuse shortwave irradiance SW_DIF W.m-2 “Diffuse” radiation is radiation that has been scattered by particles in the atmosphere such as cloud droplets and aerosols (==> diffuse solar radiation). Downwelling radiation is radiation from above. “Shortwave” means shortwave radiation, typically understood as radiation in the spectral range between ca. 0.4 µm and 4.0 µm (==> shortwave radiation). A radiative flux is identical with the quantity measured by a cosine-collector light-meter. In accordance with common usage in geophysical disciplines, “flux” implies per unit area.
RM-02 Upward thermal radiation UWIR W.m-2 Upwelling radiation is radiation from below. “Longwave” means longwave radiation, typically understood as radiation in the spectral range between ca. 4.0 µm and 25.0 µm (==> longwave radiation). A radiative flux is dentical with the quantity measured by a cosine-collector light-meter. In accordance with common usage in geophysical disciplines, “flux” implies per unit area.
RM-02 Downward thermal radiation DWIR W.m-2 Upwelling radiation is radiation from below. “Longwave” means longwave radiation, typically understood as radiation in the spectral range between ca. 4.0 µm and 25.0 µm (==> longwave radiation). A radiative flux is dentical with the quantity measured by a cosine-collector light-meter. In accordance with common usage in geophysical disciplines, “flux” implies per unit area.
RM-03 Aerosol Optical Depth AOD DL The optical Depth(OD) is the integral along the path of radiation of a volume scattering/absorption/attenuation coefficient. The radiative flux is reduced by a factor exp(-OD) on traversing the path. The atmosphere OD applies to radiation passing through the entire atmosphere. “Aerosol” means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. “Ambient_aerosol” means that the aerosol is measured or modelled at the ambient state of pressure, temperature and relative humidity that exists in its immediate environment. “Ambient aerosol particles” are aerosol particles that have taken up ambient water through hygroscopic growth.
RM-03 Angstroem exponent ANG_AOD DL The “Angstrom exponent” appears in the formula relating aerosol optical thickness (AOD) to the wavelength of incident radiation: T(lambda) = T(lambda0) * [lambda/lambda0] ** (-1 * alpha) where alpha is the Angstrom exponent, lambda is the wavelength of incident radiation, lambda0 is a reference wavelength, T(lambda) and T(lambda0) are the values of AOD at wavelengths lambda and lambda0, respectively. “Aerosol” means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. “Ambient_aerosol” means that the aerosol is measured or modelled at the ambient state of pressure, temperature and relative humidity that exists in its immediate environment. “Ambient aerosol particles” are aerosol particles that have taken up ambient water through hygroscopic growth.
RM-04 Transmission through the canopy TCNPY DL The “transmission through the canopy” (TCANOPY) refers to the amount of photosynthetically active radiation (PAR) that is transmitted through the canopy. PAR is defined as the radiation at wavelengths between ca. 400 nm and 700 nm, and is usually quantified as photosynthetic photon flux density (PPFD) in units of μmol m-2 s-1. It is the radiation within this region of the electromagnetic spectrum that is absorbed by photosynthetic pigments in plants for the purposes of photosynthesis. Tcanopy is a dimensionless quantity that ranges from 0 to 1. [GBOV]
RM-05 Surface directional-hemispherical reflectance DHR DL Reflectance is the ratio of the energy of the reflected to the incident radiation. Directional-hemispherical reflectance is the reflectance of a surface under direct illumination (with no diffuse component). Directional-hemispherical reflectance is the integral of the BRDF over all viewing directions. It is sometimes referred to as “black-sky albedo”. [GBOV]
RM-05 Surface bi-hemispherical reflectance BHR DL Reflectance is the ratio of the energy of the reflected to the incident radiation. Bi-hemispherical reflectance is the reflectance of a surface under diffuse illumination (with no direct component). Bi-hemispherical reflectance is an important part of the Bidirectional reflectance distribution function over all viewing and illumination directions of a hemisphere. It is sometimes referred to as “white-sky albedo”. [GBOV]
RM-05 Soil surface bi-directional reflectance factor BRF DL “The bi-directional reflectance factor is a function describing the anisotropy of reflected radiance from a surface illuminated from a single direction.
It is equal to π times the reflected radiance divided by the incident irradiance from a single direction.
See also “”bidirectional reflection function”” and “”bidirectional reflectance distribution”” function. [GBOV]”.
RM-06 Fraction of intercepted photosynthetically active radiation FIPAR DL The “fraction of intercepted photosynthetically active radiation” (FIPAR) refers to the amount of PAR that is intercepted by the canopy. Like FTPAR, FIPAR is a dimensionless quantity that ranges from 0 to 1. The Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), which is designated an Essential Climate Variable (ECV), is more typically the parameter of interest. However, the difference between FAPAR and FIPAR is considered minimal in most circumstances, making measurements of FIPAR suitable for validating satellite-derived FAPAR products. [GBOV]
RM-07 Leaf area index LAI m2.m-2 The “leaf area index” (LAI) in units of m2 m-2 represents the amount of leaf material in an ecosystem and is geometrically defined as the total one-sided area of photosynthetic tissue per unit ground surface area. The LAI represents the amount of leaf material in ecosystems and controls the links between biosphere and atmosphere through various processes such as photosynthesis, respiration, transpiration and rain interception. [FAO]
RM-08 Land surface emissivity LSE DL “Emissivity” is the ratio of the power emitted by an object to the power that would be emitted by a perfect black body having the same temperature as the object. The emissivity is assumed to be an integral over all wavelengths, unless a coordinate of radiation_wavelength or radiation_frequency is included to specify either the wavelength or frequency. “surface” means the lower boundary of the atmosphere. “longwave” means longwave radiation.
RM-09 Land surface temperature LST K “Surface” means the lower boundary of the atmosphere. The surface temperature is the temperature at the interface (skin temperature), not the bulk temperature of the medium above or below. Unless indicated otherwise, a quantity is assumed to apply to the whole area of each horizontal grid box.
RM-10 Soil moisture SM m3.m-3 “Condensed water” means liquid and ice. “Volume fraction” is used in the construction volume_fraction_of_X_in_Y, where X is a material constituent of Y.
RM-11 Precipitation PREC mm.h-1 Precipitation is defined as all liquid or solid phase aqueous particles that originate in the atmosphere and fall to the earth’s surface. The precipitation rate refers to the precipitation on a unit area over a fixed period of time.
Land Products (LP)
LP GBOV acronym Unit Description
LP-1 TOC-R DL

Broadband Top of Canopy reflectance

LP-2 DHR DL

Directional Hemispherical Reflectance

LP-2 BHR DL

Bi-Hemispherical Reflectance

LP-3 LAI m2.m-2

Leaf Area Index

LP-4 FAPAR DL

Fraction of Absorbed PAR

LP-5 Fcover DL

Fraction of Vegetation Cover

LP-6 SM_5 m3.m-3

Soil moisture at 5cm

LP-7 LST K

Land Surface Temperature

GBOV Documentation
ACRI-ST Logo GBOV site is hosted by ACRI-ST