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STAR / SMCD / VIIRS Aerosol Calibration and Validation

VIIRS Aerosol Product Evaluation with MODerate resolution Imaging Spectrometer (MODIS)

As the next-generation polar-orbiting operational environmental sensor with a capability for global aerosol observations, the Visible Infrared Imaging Radiometer Suite (VIIRS) is expected to continue the decade-long successful multispectral aerosol retrieval from the NASA's Earth Observing System Moderate Resolution Imaging Spectroradiometer (MODIS) for scientific research and applications. Since the launch of the Suomi National Polar-orbiting Partnership (S-NPP), the VIIRS aerosol calibration/validation team has been continuously monitoring, evaluating, and improving the performance of VIIRS aerosol retrievals. The VIIRS aerosol optical thickness (AOT) at 550 nm EDR at current Provisional maturity level is evaluated by comparing it with MODIS retrievals and measurements from the Aerosol Robotic Network (AERONET). The VIIRS global mean AOT at 550 nm differs from that of MODIS by approximately -0.01 over ocean and 0.03 over land (0.00 and -0.01 for the collocated retrievals) but shows larger regional biases. These results show that the VIIRS AOT at 550 nm product provides a solid global data set for quantitative scientific investigations and environmental monitoring (Liu et al., 2013).

The Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) aerosol optical thickness (AOT) at 550nm EDR was compared to the Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) Dark Target AOT at 550nm product (

The criteria for a S-NPP VIIRS and Aqua MODIS matchup are as follows:

  • VIIRS and MODIS retrievals are within a 5 min time interval;
  • the central location of a VIIRS EDR-aggregated retrieval box falls within the MODIS nominal 10 km retrieval domain; and
  • cloud fraction is zero within the MODIS retrieval domain to avoid possible cloud contamination. If multiple VIIRS retrievals are identified within a single MODIS 10-km box, an arithmetic average is applied to the VIIRS AOT550 to obtain a single mean value for the matchup.

For more information about the comparison between S-NPP VIIRS and Aqua MODIS AOT products, please see Liu et al. (2013, JGR)


Liu, H., L. A. Remer, J. Huang, H-C. Huang, S. Kondragunta, I. Laszlo, M. Oo, J. M. Jackson, 2013: Preliminary Evaluation of Suomi-NPP VIIRS Aerosol Optical Thickness, J. Geophys. Res., 119(7), 3942-3962. doi: 10.1002/2013jd020360