Term: ultraviolet_aerosol_index

Unit: 1

Unit ref: UUUU

AMIP:

GRIB:

ultraviolet means ultraviolet radiation, with wavelengths shorter than 400 nm. The UV-Aerosol Index is a UV color index that represents the deviation of the outgoing TOA radiation in the UV from that of a standard atmosphere, featuring Rayleigh scattering and gas absorption, in particular by ozone. No cloud droplets or suspended liquid or solid particles (aerosols) are present in the standard atmosphere. It is bounded below by a Lambertian surface, featuring isotropic reflection, assumed independent of wavelength. The ultraviolet aerosol index is computed from the Earth reflectances at two UV wavelengths. A positive deviation from the standard atmosphere is often, but not exclusively, attributed to the absorption of radiation by aerosols, while negative values represent increased scattering, not necessarily by aerosols. The wavelengths used for the computation of the ultraviolet aerosol index should be indicated using a coordinate variable with standard name radiation _wavelength and length 2. This support coordinate variable should be given in the ancillary_variables attribute. (Note: not the coordinates attribute, as this is an annotation, not a coordinate).

Term: ultraviolet_aerosol_index

Unit: 1

Unit ref: UUUU

AMIP:

GRIB:

ultraviolet means ultraviolet radiation, with wavelengths shorter than 400 nm. "Aerosol" means the system of suspended liquid or solid particles in air (except cloud droplets) and their carrier gas, the air itself. The UV-Aerosol Index is a UV color index that represents the deviation of the outgoing TOA radiation in the UV from that of a standard atmosphere, featuring Rayleigh scattering and gas absorption, in particular by ozone. No cloud droplets or suspended liquid or solid particles (aerosols) are present in the standard atmosphere. It is bounded below by a Lambertian surface, featuring isotropic reflection, assumed independent of wavelength. The ultraviolet aerosol index is computed from the Earth reflectances at two UV wavelengths. A positive deviation from the standard atmosphere is often, but not exclusively, attributed to the absorption of radiation by aerosols, while negative values represent increased scattering, not necessarily by aerosols. The wavelengths used for the computation of the ultraviolet aerosol index should be indicated using a coordinate variable with standard name radiation _wavelength and length 2. This support coordinate variable should be given in the ancillary_variables attribute. (Note: not the coordinates attribute, as this is an annotation, not a coordinate).