*Note: This dataset version has been superseded by a newer version. It is highly recommended that users access the current version. Users should only use this version for special cases, such as reproducing studies that used this version.* The product is the aerosol optical thickness (AOT) at 0.63 micron, which is retrieved from NOAA PATMOS-x level-2B orbital radinace and cloud CDR products. The retrieval is performed for selected spatial (0.1 by 0.1 degree) and temporal (1 time per day per satellite) resolution in cloud free condition during daytime. The final product is daily averaged from all satellite retrivals and in a 0.1 by 0.1 degree equal angle grid (total 1800x3600 grids over the globe). Due to the relatively large uncertainties associated with surface reflectance over water glint area and land surface as well as limited AVHRR retrieval channels, the current algorithm only performs retrieval over none-glint water surface (specifically at the anti-solar side of the orbit and viewing angle is larger than 40 degree away from the specular ray). The final CDR AOT products include daily and monthly products

*Note: This dataset version has been superseded by a newer version. It is highly recommended that users access the current version. Users should only use this version for special cases, such as reproducing studies that used this version.* This NOAA Climate Data Record (CDR) of aerosol optical thickness (AOT) at 0.63 micron is retrieved from operational AVHRR orbital pixel level observations in the Level-1B Global Area Coverage (GAC) dataset. The retrieval is performed for selected spatial (8-km) and temporal (1 time per day) resolution in cloud free condition during daytime over global oceans. The final product is mapped into 0.5 by 0.5 degree equal area grid (total 165018 grids over the globe). Due to the relatively large uncertainties associated with surface reflectance over water glint area and land surface as well as limited AVHRR retrieval channels, the current algorithm only performs retrieval over non-glint water surface (specifically at the anti-solar side of the orbit and viewing angle is larger than 40 degree away from the specular ray). The retrieval products include a daily and monthly mean product and cover the period from 1981 to 2009. Daily and monthly mean data files are grouped by ascending and descending node by satellite.

*Note: This dataset version has been superseded by a newer version. It is highly recommended that users access the current version. Users should only use this version for special cases, such as reproducing studies that used this version.* This NOAA Climate Data Record (CDR) of aerosol optical thickness (AOT) at 0.63 micron is retrieved from operational AVHRR orbital pixel level observations in the Level-1B Global Area Coverage (GAC) dataset. The retrieval is performed for selected spatial (8-km) and temporal (1 time per day) resolution in cloud free condition during daytime over global oceans. The final product is mapped into 0.5 by 0.5 degree equal area grid (total 165018 grids over the globe). Due to the relatively large uncertainties associated with surface reflectance over water glint area and land surface as well as limited AVHRR retrieval channels, the current algorithm only performs retrieval over non-glint water surface (specifically at the anti-solar side of the orbit and viewing angle is larger than 40 degree away from the specular ray). The retrieval products include a daily and monthly mean product and cover the period from 1981 to 2009. Daily and monthly mean data files are grouped by ascending and descending node by satellite.

The VIIRS/NOAA20 Dark Target Aerosol L2 6-Min Swath 6 km product provides satellite-derived measurements of Aerosol Optical Thickness (AOT) and their properties over land and ocean, and spectral AOT and their size parameters over oceans every 6 minutes, globally. The NOAA-20 - formerly the Joint Polar Satellite System-1 (JPSS-1) - Visible Infrared Imaging Radiometer Suite (VIIRS) incarnation of the dark target (DT) aerosol product is based on the same DT algorithm that was developed and used to derive products from the Terra and Aqua mission's MODIS instruments. Two separate and distinct DT algorithms exist. One helps retrieve aerosol information over ocean (dark in visible and longer wavelengths), while the second aids retrievals over vegetated/dark-soiled land (dark in the visible). This orbit-level product (Short-name: AERDT_L2_VIIRS_NOAA20) has an at-nadir resolution of 6 km x 6 km, and progressively increases away from nadir given the sensor's scanning geometry and Earth's curvature. Viewed differently, this product's resolution accommodates 8 x 8 native VIIRS moderate-resolution (M-band) pixels that nominally have ~750 m horizontal pixel size. Hence, the Level-2 Dark Target Aerosol Optical Thickness data product incorporates 64 (750 m) pixels over a 6-minute acquisition. This Version-2 set of products is the first collection of the Level-2 Dark Target Aerosol derived from the NOAA-20 VIIRS source. Hence, it bears outlining the differences between the products derived from NOAA-20 VIIRS as against the Suomi National Polar-orbiting Partnership (SNPP) VIIRS. For more information consult LAADS product description page at: https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/AERDT_L2_VIIRS_NOAA20 Or, Dark Target aerosol team Page at: https://darktarget.gsfc.nasa.gov/