The Visible Infrared Imaging Radiometer Suite (VIIRS) NASA standard Level 3 (L3) monthly Deep Blue Aerosol Products from the Joint Polar Satellite System (JPSS) series NOAA-20 instrument provide satellite-derived measurements of Aerosol Optical Thickness (AOT) and their properties over land and ocean as gridded aggregates, globally on a monthly basis. The Deep Blue algorithm draws its heritage from previous applications to retrieve AOT from Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) over both land and ocean, and Moderate Resolution Imaging Spectroradiometer (MODIS) measurements over land.

This monthly aggregated product (Short-name: AERDB_M3_VIIRS_NOAA20) is derived from the Version 2.1 (v2.1) daily L3 gridded products (AERDB_D3_VIIRS_NOAA20) and is provided in a 1^o x 1^o horizontal-resolution grid. Arithmetic mean values from the daily L3 gridded products also provide the basis to derive a complement of statistics for the monthly aggregated products. To exclude poorly sampled grid elements, the algorithm requires at least 3 valid days' worth of data to render a given monthly grid element as valid. This collection’s product record starts on January 5, 2018 (2018-005).

This L3 monthly product, in netCDF, contains 45 Science Data Set (SDS) layers that have names identical to the SDSs in the daily L3 product, and include the following:

1. Aerosol_Optical_Thickness_550_Land_Count
2. Aerosol_Optical_Thickness_550_Land_Maximum
3. Aerosol_Optical_Thickness_550_Land_Mean
4. Aerosol_Optical_Thickness_550_Land_Minimum
5. Aerosol_Optical_Thickness_550_Land_Ocean_Count
6. Aerosol_Optical_Thickness_550_Land_Ocean_Maximum
7. Aerosol_Optical_Thickness_550_Land_Ocean_Mean
8. Aerosol_Optical_Thickness_550_Land_Ocean_Minimum
9. Aerosol_Optical_Thickness_550_Land_Ocean_Standard_Deviation
10. Aerosol_Optical_Thickness_550_Land_Standard_Deviation
11. Aerosol_Optical_Thickness_550_Ocean_Count
12. Aerosol_Optical_Thickness_550_Ocean_Maximum
13. Aerosol_Optical_Thickness_550_Ocean_Mean
14. Aerosol_Optical_Thickness_550_Ocean_Minimum
15. Aerosol_Optical_Thickness_550_Ocean_Standard_Deviation
16. Aerosol_Type_Land_Ocean_Histogram
17. Aerosol_Type_Land_Ocean_Mode
18. Aerosol_Types
19. Angstrom_Exponent_Land_Maximum
20. Angstrom_Exponent_Land_Mean
21. Angstrom_Exponent_Land_Minimum
22. Angstrom_Exponent_Land_Ocean_Maximum
23. Angstrom_Exponent_Land_Ocean_Mean
24. Angstrom_Exponent_Land_Ocean_Minimum
25. Angstrom_Exponent_Land_Ocean_Standard_Deviation
26. Angstrom_Exponent_Land_Standard_Deviation
27. Angstrom_Exponent_Ocean_Maximum
28. Angstrom_Exponent_Ocean_Mean
29. Angstrom_Exponent_Ocean_Minimum
30. Angstrom_Exponent_Ocean_Standard_Deviation
31. Fine_Mode_Fraction_550_Ocean_Mean
32. Fine_Mode_Fraction_550_Ocean_Standard_Deviation
33. Land_Bands
34. Latitude
35. Latitude_1D
36. Longitude
37. Longitude_1D
38. Ocean_Bands
39. Spectral_Aerosol_Optical_Thickness_Land_Count
40. Spectral_Aerosol_Optical_Thickness_Land_Mean
41. Spectral_Aerosol_Optical_Thickness_Land_Standard_Deviation
42. Spectral_Aerosol_Optical_Thickness_Ocean_Count
43. Spectral_Aerosol_Optical_Thickness_Ocean_Mean
44. Spectral_Aerosol_Optical_Thickness_Ocean_Standard_Deviation
45. Unsuitable_Pixel_Fraction_Land_Ocean

Differences Between the v2.1 and v2.0 VIIRS Deep Blue Aerosol Collections

• VIIRS-derived Deep Blue Aerosol Products are now available from the NOAA-21, NOAA-20, and Suomi National Polar-orbiting Partnership (SNPP) platforms.
• Dome C (a calibration site in eastern Antarctica) cross-calibration between SNPP and NOAA-21 has been incorporated to ensure radiometric consistency.
• AOT spatial distribution has been improved over North Africa (particularly between the Sahara and Sahel regions) and South Asia (around the Thar Desert and Indus River Basin).
• Aerosol optical models (i.e., single-scattering albedo) have been adjusted over North America, the Sahel, Southern Africa, and India to further optimize retrieval performance.* More rigorous Sun-glint screening has been implemented for over-water retrievals, reducing contamination at the expense of some spatial coverage.
  Cloud filters have been revised to better retain heavy dust plumes and to better remove thin clouds and sea fog over water.

Consult the VIIRS Deep Blue Aerosol Product User Guide for additional information regarding the global attributes, data field attributes, quality flags, software for handling and using these data products, and other relevant information.