Sun photometer radiance measurements can be inverted to produce aerosol optical properties such as size distribution, single scattering albedo, phase functions, and the complex index of refraction. Sun photometers measure the radiance at four or more wavelengths using almucantar and principle plane scenarios. The almucantar scenario measures radiance at azimuthal angles relative to the sun. For at least single-scattering approximation, sky radiances in the almucantar are not sensitive to aerosol vertical variations. The principle plane scenario measures radiance at scattering angles away from the sun. These radiance data in combination with aerosol optical depth measurements and estimations of land and water surface reflectance are inverted to estimate aerosol optical properties.
Version 2 inversion data are provided as one model product with additional parameters such as sphericity, radiative forcing and spectral flux. Version 2 inversions will be released as Levels 1.5 and 2.0, based on the level of aerosol optical depth (AOD) and other quality almucantar and principle plane checks.
Data may be viewed and downloaded using the links in the left menu bar under Aerosol Inversions. To learn more about the Version 2 data products, please read the following documents:
+ Version 2 Inversion Product Descriptions (PDF)
+ Version 2 Quality Assurance Criteria or Full Version (PDF)
Radiance data are normalized using the extraterrestrial solar irradiance spectra (2000 ASTM Standard Extraterrestrial Spectrum Reference E-490-00).
*Note: Version 1 inversion data are provided in aerosol spherical and spheroid models. These data are provided in Levels 1.5 and Level 2.0 based on the AOD level and other quality checks. These inversion products may be accessed through the data synergy tool.