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STAR / SMCD / VIIRS Aerosol Calibration and Validation

VIIRS Aerosol Product Evaluation

The VIIRS aerosol products are evaluated to establish their level of maturity. (See the page Maturity Level Definition for definition of the levels.) In the evaluation the quality of the aerosol products are assessed by comapring the VIIRS products with like products obtained from independent satellite retrievals and ground measurements.

Data quality assessment objective

The analysis, which the assessment is based on, attempts to answer the following questions:

  • Which products and fields have value and are ready for a particular maturity level?
  • Can specific code changes and/or paths of analysis that make significant improvements to the product before the products are advanced to the next stage be suggested?
  • How well do the AOT and APSP products match collocated Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals?
  • How well do the AOT and APSP products match collocated AErosol RObotic NETwork (AERONET) observations and retrievals?
  • How well do the ASOT and APSP products represent the global aerosol system during the period of analysis, without benefit of MODIS or AERONET’s collocations to choose conditions?
  • Does the global distribution of suspended matter match our expectations based on EOS-era satellite retrievals and model results?
  • How does the suspended matter product compare with Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) designations of smoke and dust aerosol?

Data quality assessment methods

The VIIRS AOT and APSP products have been compared with aerosol products derived from MODIS observations onboard the NASA Earth Observing System (EOS) satellites (Aqua), and with AERONET products and observations. VIIRS Suspended Matter has been compared with CALIPSO products.

Comparisons include direct collocations of various match-up criteria and assessments of monthly statistics without the benefit of direct collocation.

The time period used is sufficient to identify major and obvious problems with the products, and to provide a preliminary bound on the products' uncertainties. The uncertainties stated here will change as additional months of data are analyzed.

Both qualitative and quantitative assessments are made. The qualitative assessment compares maps of VIIRS aerosol EDRs to similar products from MODIS and CALIPSO to show that the VIIRS products indeed “look like” aerosol products. The quantitative assessment describes the level of agreement in terms of accuracy (bias) and precision (standard deviation of differences between retrievals and reference data).

Results of the evaluation for the Provisional Maturity level are presented on these pages: