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STAR / SMCD / VIIRS Aerosol Calibration and Validation

VIIRS Aerosol Data Products

Aerosol in the VIIRS processing system is processed from the VIIRS Sensor Data Records (SDRs) and ancillary data on a granule by granule basis. One VIIRS granule typically consists of 768 x 3200 (along-track by cross-track) 750 m pixels. The results of the pixel-level retrievals are the Intermediate Products (IPs) consisting of aerosol optical thickness (AOT), aerosol particle size parameter (APSP), aerosol model retrieved, and associated quality flags.

Using various combinations of the quality flags, and aggregation of 8 x 8 AOT and APSP IPs, Environmental Data Records (EDRs) are created from the IPs.

Overview of VIIRS aerosol data products
Parameter Name Units Horizontal Cell Size (HCS) at Nadir Comments
Aerosol Optical Thickness (AOT) Dimensionless 6 km (EDR)
0.75 km (IP)
Retrieved globally during daylight except areas of clouds and bright surfaces. Reported at eleven wavelengths ranging from 0.412-2.25 µm.
Aerosol Particle Size Parameter(APSP) Dimensionless 6 km (EDR)
0.75 km (IP)
Reported as Ångström Exponent calculated from optical depths at pairs of wavelengths. Only proxy, not a true measure of size.
Suspended Matter (SM) Dimensionless (except, smoke concentration in µg/m3) 0.75 km (EDR) Type of aerosol (ash, dust, smoke, sea salt, unknown, none) for moderate to heavy aerosol loading, for AOT larger than threshold.

The VIIRS aerosol products reach various levels of maturity as algorithm changes are implemented and as the quality of products are assessed. The maturity levels are Beta, Provisional and Validated. These correspond to specific criteria detailed in VIIRS Aerosol Product Maturity Levels.

Product timeline

Product timeline

Red period: Product is not available to public, or product should not be used.

Blue period: Product is available to public, but it should be used with caution, known problems, frequent changes.

Green period: Product is available to public; meets the threshold performance attributes identified in the JPSS Level 1 Requirements Supplement.

Current Status:

  • AOT: Validated Stage 2;
  • APSP: Validated Stage 1.

Data Access

The granule-based EDRs and IPs are the official products distributed through the NOAA Comprehensive Large Array-data Stewardship System (CLASS).

STAR also generates a gridded AOT product from the high-quality aerosol optical depth EDRs.

The links below provide details of these products and give instructions on how to access them: