MODIS Collection 6 Dark Target
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MODIS Collection 6 "Dark Target" The “dark-target” (DT) algorithm retrieves aerosol properties over oceans and primarily vegetated (“dark”) land surfaces. The quantitative products include total aerosol optical depth (AOD) over both ocean and land, and a measure of size distribution known as fine mode weighting (FMW) over ocean. Starting with Collection 6 (C6), the DT family includes products at two spatial resolutions: 10 x 10 km resolution (at nadir) (MxD04_L2; MOD04 for Terra and MYD04 for Aqua), 3 x 3 km product for air quality applications (MxD04_3K). MxD04 includes also other variables (derived aerosol properties, .e.g. Angstrom Exponent, columnar Mass Concentrations; diagnostics, e.g. Quality assurance, cloud fraction). MxD04_L2 also contains an additional AOD product with a statistical “merging” of the DT and the “deep-blue” (DB) AOD.
Example result / latest result (if near-real time)
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Satellite |
EOS Terra / EOS Aqua |
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Instrument(s) |
MODIS (Moderate-resolution Imaging Spectroradiometer) |
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Contact details |
robert.c.levy[at]nasa.gov |
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Parameter(s) |
AOD, Angstrom exponent, fine mode ratio (over ocean) |
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Aerosol algorithm |
“Dark-target” (DT); separate algorithm over ocean and land |
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Cloud screening |
MOD35 + internal tests |
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Aerosol model |
Ocean: Theoretical (pairing of fine and coarse modes with choice); Land: derived from AERONET climatology (prescribed pairing of fine and coarse models) |
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Retrieval assumptions |
Aerosol models: Bimodal (fine + coarse); flexible over ocean, prescribed over land. Surface optical properties: Ocean: rough ocean a function of wind speed, Land: parameterized relationship between wavelength bands |
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Retrieval limitations |
No retrieval over bright surfaces which include: ice/snow, glint over ocean and arid/desert regions over land |
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Spatial, temporal coverage |
2000 - present (Terra), 2002 - present (Aqua), Standard and NRT, 2 day global |
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Spatial, temporal resolution |
10 km and 3 km / 2330 km swath / 16 day repeat cycle |
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Operations status |
Standard: operational / reprocessing (complete time series) NRT: operational, latency of ~90 minutes |
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Validation status |
2000-present online access to validation results |
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Quality control |
pixel-wise quality assurance and confidence flags |
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last algorithm version |
collection 6 (began 2014) |
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last validation |
2015 |
| Algorithm description | Product format description |
| Version explanation | Validation summary |
| Publications |
| Product data access |
| Image / quicklook data access |