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The effect of aerosols is one of the greatest sources of uncertainty in climate modeling. Aerosols vary in time in space and can lead to variations in cloud microphysics, which impact cloud radiative properties and climate. The Dark-Target (DT) aerosol retrieval algorithm is applied to multispectral satellite sensor data, and derives aerosol properties including aerosol optical depth (AOD) over land and ocean, as well as spectral AOD and aerosol size parameters over ocean. Products of the DT retrieval are used to develop global and regional aerosol climatology, to study the interaction of aerosols with clouds, and for air quality assessments and forecasts.

The DT algorithm has been applied to data from the MODIS sensor beginning with the Terra satellite in 1999 and followed by Aqua in 2001. There are actually two separate and distinct “Dark Target” (DT) algorithms. The first one is used for retrieving aerosol information over ocean (dark in visible and longer wavelengths) and the second one over vegetated/dark-soiled land (dark in the visible).   The algorithms have been refined and improved continually since the launch of Terra.  The updated algorithms are applied to the raw data periodically to produce new data product collections.  Currently Terra and Aqua data products are collection 6 (C6).

Although originally developed for use with the MODIS sensors these algorithms can be applied to any sensor that measures reflectance in appropriate wavelength bands covering  visible (VIS), near-IR (NIR) and shortwave-IR (SWIR). Currently the DT retrieval algorithm is being ported to additional sensors including VIIRS on SUOMI-NPP, AHI (Himawari) , EPIC (DISCOVR) and the airborne sensor eMAS usually flown on the ER2 and will be applied in the near future to ABI (GOES-R-16).

Dark Target Website