AERDT_L2_VIIRS_SNPP - VIIRS/SNPP Dark Target Aerosol L2 6-Min Swath 6 km



The Suomi National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) NASA standard Level-2 (L2) dark target (DT) aerosol 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 VIIRS incarnation of the 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_SNPP) 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 L2 DT AOT data product incorporates 64 (750 m) pixels over a 6-minute acquisition. In contrast to collection-001 of this product, this collection-011 uses bowtie-restored pixels that are used for both cloud masking and for performing some retrievals using the restored pixels as well.

The L2 netCDF product contains the following 37 Science Data Set (SDS) layers:

  1. Aerosol_Cldmask_Land_Ocean
  2. Aerosol_Cloud_Fraction_Land
  3. Aerosol_Cloud_Fraction_Ocean
  4. Aerosol_Type_Land
  5. Angstrom_Exponent_1_Ocean
  6. Angstrom_Exponent_2_Ocean
  7. Asymmetry_Factor_Average_Ocean
  8. Average_Cloud_Pixel_Distance_Land_Ocean
  9. Backscattering_Ratio_Average_Ocean
  10. Cloud_Pixel_Distance_Land_Ocean
  11. Corrected_Optical_Depth_Land
  12. Effective_Optical_Depth_Average_Ocean
  13. Effective_Radius_Ocean
  14. Error_Flag_Land_And_Ocean
  15. Fitting_Error_Land
  16. Image_Optical_Depth_Land_And_Ocean
  17. Land_Ocean_Quality_Flag
  18. Land_Sea_Flag
  19. Least_Squares_Error_Ocean
  20. Mass_Concentration_Land
  21. Mass_Concentration_Ocean
  22. Mean_Reflectance_Land
  23. Mean_Reflectance_Ocean
  24. Number_Pixels_Used_Land
  25. Number_Pixels_Used_Ocean
  26. Optical_Depth_By_Models_Ocean
  27. Optical_Depth_Land_And_Ocean
  28. Optical_Depth_Large_Average_Ocean
  29. Optical_Depth_Ratio_Small_Land
  30. Optical_Depth_Ratio_Small_Ocean_0p55micron
  31. Optical_Depth_Small_Average_Ocean
  32. PSML003_Ocean
  33. STD_Reflectance_Land
  34. STD_Reflectance_Ocean
  35. Surface_Reflectance_Land
  36. Topographic_Altitude_Land
  37. Wind_Speed_Ncep_Ocean

Consult the NASA MODIS and VIIRS Dark Target Aerosol Product User Guide for additional information regarding these SDS parameters.

Links


Shortname: AERDT_L2_VIIRS_SNPP
Platform: Suomi-NPP
Instrument: VIIRS
Processing Level: Level-2
File Size (MB): 7 - 12 MB
Data Format: netCDF4
Spatial Resolution: 6km
Temporal Resolution: 6 minute
Spatial Coverage: Global (daytime only)
ArchiveSets: 5111
Collection: NPP VIIRS Atmosphere data 1.1.0 (UWisc) (ArchiveSet 5111)
Production Frequency: ~130 files/day
Data Authors: R.C. Levy, S. Mattoo, V. Sawyer, L.A. Munchak
Dataset Originator/Creator: Dark Target aerosol team, Climate and Radiation Laboratory, NASA Goddard Space Flight Center
PGE Number: NONE
File Naming Convention:

Example: AERDT_L2_VIIRS_SNPP.A2019218.1818.001.2019291174906.nc

  • Syntax: ESDT.AYYYYDDD.HHMM.CCC.YYYYDDDHHMMSS.Format
  • ESDT = Earth Science Data Type or Shortname
  • A = Stands for Acquisition
  • YYYYDDD = Data acquisition year and Day-of-year
  • HHMM = Acquisition Hour and Minute
  • CCC = Version ID of the data collection
  • YYYYDDDHHMMSS = Processing year, Day-of-year, UTC time (hour, minutes, seconds)
  • Format = File format suffix, which in the above case represents netCDF4
Citation: We kindly request that you cite the use of this data set in a publication using the following references:

Sawyer, V., R.C. Levy, S. Mattoo, G. Cureton, Y. Shi, and L.A. Remer (2020), Continuing the MODIS Dark Target Aerosol Time Series with VIIRS. Remote Sens. 2020, 12, 308; https://doi.org/10.3390/rs12020308

Levy, R.C., L. A. Munchak, S. Mattoo, F. Patadia, L. A. Remer, and R. E. Holz (2015), Towards a long-term global aerosol optical depth record: applying a consistent aerosol retrieval algorithm to MODIS and VIIRS-observed reflectance, Atmos. Meas. Tech., 8, 4083–4110.
Keywords: SNPP VIIRS, L2 Swath, 6-Minute, Dark Target Aerosol Optical Thickness
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