VIIRS Aerosol (AERDB·AERDT)¶

VIIRS Deep Blue Aerosol (AERDB_L2, AERDB_D3, AERDB_M3) and Dark Target Aerosol (AERDT_L2) Version 2.1 — Suomi NPP, NOAA-20, NOAA-21 (VIIRS aerosol optical depth continuing the MODIS record)

Available

At a glance¶

Note on period: Suomi NPP from 2012-03-01 (delivery due to end 2026-11-02), NOAA-20 from early 2018 (DB V2.1 2018-01-05, DT 2018-02-17), NOAA-21 from 2023-02-10. Deep Blue has L2 plus 1° daily and monthly L3; Dark Target has L2 only at LAADS (checked 2026-10-13).

Overview¶

NASA continuity aerosol products that apply the two MODIS aerosol algorithms to VIIRS so the MODIS record can continue. Deep Blue (AERDB) retrieves 550 nm aerosol optical depth (AOD) with Deep Blue over land and the SOAR algorithm over ocean, holding land and ocean together, and also comes as 1° daily and monthly grids. Dark Target (AERDT) is an L2 product that follows the MODIS DT approach over ocean and dark vegetated land. There are Suomi NPP, NOAA-20 and NOAA-21 versions, all in orbits passing around 1:30 pm, so they mainly continue MODIS Aqua. Unlike MODIS, there is no combined DT+DB AOD.

What changes with the successor¶

VIIRS Deep Blue V2.0 / Dark Target V2.0 → VIIRS Deep Blue V2.1 / Dark Target V2.1¶

Transition: 2026-09

Dark Target V2.1 was released in December 2025 and Deep Blue V2.1 in September 2026, adding NOAA-21 versions. Both add cross-calibration between satellites to reduce AOD differences between them. DT V2.0 was decommissioned on 2026-08-31; DB V2.0 remains available alongside until 2027-03-31.

Sources: Version 2.1 VIIRS Deep Blue Aerosol Data Products Released (LAADS, 2026-09-14) · AERDT_L2_VIIRS_SNPP V2.1 collection description (CMR metadata) · V2.1 Level-2 Dark Target Aerosol Data Products Released (LAADS, 2025-12-18)

Available variables¶

Names from the CMR variable records (UMM-Var) and collection descriptions. Files are NetCDF-4 (CF 1.6) and open directly in xarray or netCDF4. Deep Blue variables sit at the top level of the file; Dark Target variables are inside the geophysical_data/ group. AOD is dimensionless and referenced to 550 nm. Variable names are the same in NOAA-20, NOAA-21 and SNPP files. The DB fill value is -999.

instantaneous mean accumulated maximum minimum static — instantaneous: value at the time stamp · mean/accumulated/maximum/minimum: over the indicated interval · static: does not change with time

Deep Blue L2 swath 6 km (AERDB_L2_VIIRS_NOAA20, NOAA21, SNPP)¶

Dark Target L2 swath 6 km (AERDT_L2_VIIRS_NOAA20, NOAA21, SNPP)¶

Deep Blue L3 daily 1° (AERDB_D3_VIIRS_NOAA20, NOAA21, SNPP)¶

Deep Blue L3 monthly 1° (AERDB_M3_VIIRS_NOAA20, NOAA21, SNPP)¶

The full variable list is in the official documentation.

How to get the data¶

• LAADS DAAC (search, order and direct download) — Web search, direct HTTPS download (archive/allData/5201// for V2.1) / LAADS API-V2 / OPeNDAP
  • Example short names: AERDB_L2_VIIRS_NOAA20, AERDB_D3_VIIRS_NOAA20, AERDB_M3_VIIRS_NOAA20, AERDT_L2_VIIRS_NOAA20 (NOAA21 for NOAA-21, SNPP for Suomi NPP). The CMR version is "2.1" for V2.1 and "2" for DB V2.0. Since 2026-04-30 OPeNDAP also requires Earthdata Login, and the old LAADS Classic API was retired on 2026-08-31, so scripts must move to API-V2.
• NASA Earthdata Search — Web search / earthaccess (Python)
  • Searching AERDB or AERDT lists collections by satellite and version. Choose V2.1.
• Near-real-time Dark Target (Atmosphere SIPS) — Web search / HTTPS
  • AERDT_L2_VIIRS_NOAA20_NRT and AERDT_L2_VIIRS_SNPP_NRT (v2.2 from 2026-07-01). For rapid monitoring; use the standard product for research time series.

Example code¶

Downloads a NOAA-20 Deep Blue monthly file (V2.1) with earthaccess and reads the monthly land and ocean AOD with xarray. Check coordinate names with print(ds).

# pip install earthaccess xarray netCDF4
import earthaccess
import xarray as xr

earthaccess.login()  # free NASA Earthdata account
results = earthaccess.search_data(
    short_name="AERDB_M3_VIIRS_NOAA20", version="2.1",
    temporal=("2024-04-01", "2024-04-30"),
)
files = earthaccess.download(results[:1], "aerdb")

ds = xr.open_dataset(files[0])          # NetCDF-4; fill values (-999) become NaN
print(ds)                               # check variable and coordinate names
aod = ds["Aerosol_Optical_Thickness_550_Land_Ocean_Mean"]
ndays = ds["Aerosol_Optical_Thickness_550_Land_Ocean_Count"]
print(float(aod.where(ndays >= 10).mean()))   # only cells with at least 10 valid days

Practical tips¶

• The Suomi NPP versions stop after 2026-11-02. To continue an SNPP-based record, check the differences between satellites over an overlap period (NOAA-20 from 2018, NOAA-21 from 2023) before switching. For DT V2.0, SNPP AOD is higher than NOAA-20 and has a larger positive bias against AERONET (Sawyer et al., 2025).
• AERDB holds land (Deep Blue) and ocean (SOAR) together, but the ocean quality flag uses only 0, 1 and 3 while land uses 0–3. For quantitative work use the _Best_Estimate fields, which keep only quality 2 and 3.
• There is no VIIRS variable equivalent to the MODIS combined (DT+DB) AOD. For long-term work, pick DB (AERDB) or DT (AERDT) and compare with the same-algorithm MODIS record.
• DT is available only as L2 at LAADS (checked 2026-10). If you need gridded data, aggregate it yourself (to 1° or similar) and keep the quality 3 filter over land.
• DB V2.1 screens sun glint over water more strictly, reducing ocean coverage, and its cloud screening now keeps more heavy dust. Do not mix V2.0 and V2.1 (V2.0 stays available until 2027-03-31).
• Suomi NPP had several anomalies in 2026 (9–13 March, 10–17 July, 2–6 August) that left gaps, and in July data from 1 May onward were regenerated with new calibration tables. When using SNPP data from 2026, check the production date.
• AOD is not the same thing as surface PM2.5. It is column-integrated extinction, so its relationship with surface concentration depends on boundary layer height and humidity.

Notices and change history¶

References for your paper¶

Dataset citation¶

AERDB_L2_VIIRS_NOAA20 V2.1 (NOAA-20 Deep Blue L2) — DOI 10.5067/VIIRS/AERDB_L2_VIIRS_NOAA20.021

@misc{aerdb_l2_noaa20_v21,
  author    = {{NASA VIIRS Atmosphere SIPS}},
  title     = {{NOAA20 VIIRS} {Deep Blue} Aerosol Level 2 6-Min Swath 6 km, Version 2.1},
  year      = {2026},
  publisher = {L1 and Atmosphere Archive and Distribution System (LAADS)},
  doi       = {10.5067/VIIRS/AERDB_L2_VIIRS_NOAA20.021}
}

AERDB_M3_VIIRS_NOAA20 V2.1 (NOAA-20 Deep Blue monthly) — DOI 10.5067/VIIRS/AERDB_M3_VIIRS_NOAA20.021

@misc{aerdb_m3_noaa20_v21,
  author    = {{NASA VIIRS Atmosphere SIPS}},
  title     = {{NOAA20 VIIRS} {Deep Blue} Level 3 Monthly Aerosol Data, 1x1 Degree Grid, Version 2.1},
  year      = {2026},
  publisher = {L1 and Atmosphere Archive and Distribution System (LAADS)},
  doi       = {10.5067/VIIRS/AERDB_M3_VIIRS_NOAA20.021}
}

AERDT_L2_VIIRS_NOAA20 V2.1 (NOAA-20 Dark Target L2) — DOI 10.5067/VIIRS/AERDT_L2_VIIRS_NOAA20.021

@misc{aerdt_l2_noaa20_v21,
  author    = {{NASA VIIRS Atmosphere SIPS}},
  title     = {{NOAA20 VIIRS} {Dark Target} Aerosol Level-2 6-Minute Swath 6 km, Version 2.1},
  year      = {2025},
  publisher = {L1 and Atmosphere Archive and Distribution System (LAADS)},
  doi       = {10.5067/VIIRS/AERDT_L2_VIIRS_NOAA20.021}
}

Reference papers¶

VIIRS Version 2 Deep Blue products (Lee et al., 2024) — DOI 10.1029/2023JD040082

@article{lee2024viirsdb,
  author  = {Lee, J. and Hsu, N. C. and Kim, W. V. and Sayer, A. M. and Tsay, S.-C.},
  title   = {{VIIRS} {Version 2} {Deep Blue} aerosol products},
  journal = {Journal of Geophysical Research: Atmospheres},
  volume  = {129},
  pages   = {e2023JD040082},
  year    = {2024},
  doi     = {10.1029/2023JD040082}
}

VIIRS Deep Blue products over land (Hsu et al., 2019) — DOI 10.1029/2018JD029688

@article{hsu2019viirsdb,
  author  = {Hsu, N. C. and Lee, J. and Sayer, A. M. and Kim, W. and Bettenhausen, C. and Tsay, S.-C.},
  title   = {{VIIRS} {Deep Blue} aerosol products over land: Extending the {EOS} long-term aerosol data records},
  journal = {Journal of Geophysical Research: Atmospheres},
  volume  = {124},
  pages   = {4026--4053},
  year    = {2019},
  doi     = {10.1029/2018JD029688}
}

Continuing the MODIS Dark Target time series with VIIRS (Sawyer et al., 2020) — DOI 10.3390/rs12020308

@article{sawyer2020viirsdt,
  author  = {Sawyer, V. and Levy, R. C. and Mattoo, S. and Cureton, G. and Shi, Y. and Remer, L. A.},
  title   = {Continuing the {MODIS} {Dark Target} Aerosol Time Series with {VIIRS}},
  journal = {Remote Sensing},
  volume  = {12},
  number  = {2},
  pages   = {308},
  year    = {2020},
  doi     = {10.3390/rs12020308}
}

Updated VIIRS Dark Target, MODIS continuity and regional trends (Sawyer et al., 2025) — DOI 10.3389/fenvs.2025.1602145

@article{sawyer2025viirsdt,
  author  = {Sawyer, V. and Levy, R. C. and Mattoo, S. and Shi, Y. R. and Kim, M. and Remer, L. A. and Cureton, G.},
  title   = {An updated {VIIRS} dark target aerosol product for continuity with {MODIS}: assessing regional aerosol trends},
  journal = {Frontiers in Environmental Science},
  volume  = {13},
  pages   = {1602145},
  year    = {2025},
  doi     = {10.3389/fenvs.2025.1602145}
}

Acknowledgements¶

Cite the LAADS dataset DOI of each product and satellite you use (pattern 10.5067/VIIRS/.021, e.g. 10.5067/VIIRS/AERDB_D3_VIIRS_NOAA21.021 for NOAA-21 DB daily). The Deep Blue user guide suggests the acknowledgement "We thank the Deep Blue science team (https://deepblue.gsfc.nasa.gov) for the VIIRS Deep Blue aerosol data record." The Dark Target product page asks users to cite Sawyer et al. (2025), Sawyer et al. (2020) and Levy et al. (2015, AMT, doi:10.5194/amt-8-4083-2015).

Information on the datasets used in this study was compiled with the help of the Korean Climate Data Navigator (KCDN) (Sim, 2026; https://doi.org/10.5281/zenodo.23300923).

Links¶

• AERDB_L2_VIIRS_NOAA20 product page (LAADS DAAC)
• AERDT_L2_VIIRS_NOAA20 product page (LAADS DAAC)
• VIIRS Deep Blue Aerosol User's Guide (2026-08)
• VIIRS Deep Blue Aerosol ATBD (2025-03)
• VIIRS Dark Target User's Guide (2025-04)
• Dark Target ATBD (MODIS and VIIRS)
• LAADS DAAC — MODIS to VIIRS Transition
• Suomi NPP Data Product Delivery to Cease (Earthdata)