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STAR / SMCD / VIIRS Aerosol Calibration and Validation

Known Issues to Date

The following are known issues with the VIIRS Aerosol IP/EDR:

  • There is a slight positive bias over land. Only best quality IP/EDR data should be used!
  • There is an artificially high AOT in the snow melt region in the data before Jun 22, 2015. New snow and snow melt tests that significantly reduce snow and snow melt contaminations were transferred to operation on June 22, 2015.
  • Negative AOT bias over ocean in dust outflow regions.
  • The proportion of AOT attributed to small particles is too high over ocean.
  • There are missing data in the bowtie deletion region.
  • Internal ephemeral water test was found overscreening heavy smoke plumes. This internal test was removed from the operation on December 17, 2015. External ephemeral water test from the cloud mask product remains.
  • Internal bright surface test was found with limited coverage of bright surface regions. A fix was transferred to operation on December 17, 2015, and the new internal test is able to identify bright surface regions reasonably well after that date.
  • The Angstrom Exponent out of range flag occurs only at extreme high latitudes, which seems unlikely.
  • The “Bad SDR Data” quality flag is too omnipresent.
  • In heavy dust/smoke plume regions, AOT could be flagged as out of range.
  • There is no skill in retrieving APSP information over land; this product should not be used.
  • Overabundance of smoke, and not enough dust in Suspended Matter product.
  • There are no retrievals over inland water bodies; this is by design.
  • An inadvertent error introduced in the operational aerosol code resulted in significantly degraded aerosol EDRs for the period 10/15/2012 to 11/27/2012, invalidating the aerosol beta maturity results. Users should be aware that within this timeframe, AOT values were retrieved for confidently cloudy areas (as determined by the VIIRS cloud mask) where there should not have been retrievals, leading to increased AOT values and significantly degraded products.