STAR Joint Polar Satellite System Algorithms & Data Products website National Oceanographic & Atmospheric Administration website NOAA Center for Satellite Applications and Research website
Aerosol Optical Thickness, 3/19/2016 - click to enlarge

Aerosol Optical Thickness, 3/19/2016 - click to enlarge


Team Leads:

Product Description

EPS AOD, APSP Algorithm Overview (AOD):

  • EPS: Enterprise Processing System;
    AOT/AOD: Aerosol Optical Thickness/Depth;
    APSP: Aerosol Particle Size Parameter
  • Designed to work with VIIRS and ABI (AHI) observations
  • Separate algorithms over land and water:
    • Water: MODIS heritage; Includes large inland water bodies
    • Land: separate paths for dark and bright surface:
      Dark surface: combines two "flavors" of the "dark-target" approach;
      Bright (snow-free) surface: regional ratios of surface reflectances
  • Uses SW for AOD, SW+IR for internal test, masks (cloud, snow/ice, etc.), ancillary data (P, TPW, ozone, wind)

EPS AD (Aerosl Detection) Algorithm Overview (ADP):

  • Input Reflectances: 412, 440, 2250 µm
  • Internal Tests:
    Spatial Variability Test: 412 µm (land); 865 µm (water)
    Turbid Water Test: 488 µm, 1.24 µm, 1.61 µm, 2.25 µm
    Bright Pixel Test:1.24 µm, 2.25 µm
    NDVI Test: 640 µm, 865 µm
    Snow Test: 865 µm, 1.24 µm + IR
  • Absorbing Aerosol Index (AAI); Dust Smoke Discrimination Index (DSDI)

Product and Data Access

Products and data:

EDR Long Term-Monitoring


EPS AOD, APSP Algorithm Output:

AOD at 550 µm and at SW channels (M1 to M11; AOD range: -0.05 to 5.0); ÂngstrÕm exponents calculated from AOD at two pairs of wavelengths (M4,M7 and M7,M10 µm) over ocean

EPS AD Algorithm Output:

Dust, Smoke, Ash products


NOAA Earth System Research Laboratory (ESRL); NOAA Joint Center for Satellite Data Assimilation (JCSDA); NOAA National Centers for Environmental Prediction (NCEP) Environmental Modeling Center (EMC); University at Albany, State University of New York; Naval Research Laboratory (NRL); NOAA Ocean & Atmospheric Research (OAR)

Future Improvements


  • Update spectral surface reflectance relationships to minimize seasonal and regional biases
  • Examine causes of systematic error in spectral AOD; apply fix


  • Account for surface contribution to TOA reflectances in computing absorbing aerosol index
  • Introduce geometry and location dependent thresholds used in spectral tests
  • Develop an approach to determine surface smoke and dust concentrations