At this point, the MODIS aerosol team has not evaluated the reliability of other parameters, including certain derived parameters (e.g. Mass Concentration) and diagnostic parameters (cloud fraction). The user is cautioned that there is no expected quantitative value to these parameters. 

In Collection 6, the preliminary estimate error is 0.45; pixels with an AOD > 0.2 are expected to have a more accurate Angstrom Exponent.

In collection 5 the estimated errors are:

   Land:   AOD * 0.15 +/- 0.05

   Ocean: AOD * 0.05 +/- 0.03

 These are global estimates from the entire data set.  Errors in the product vary from region to region and season to season. For a site by site analysis see the maps in our “Validation” section. The Collection 6 product is currently being analyzed and error estimates have not yet been published.

MODIS data is inter-compared with data collected from the AERONET worldwide network of ground stations (See http://aeronet.gsfc.nasa.gov).  The MODIS and AERONET data are temporally and spatially matched using the following criteria:

Temporal:  All AERONET observations made within +/- 30 minutes of a MODIS overpass at an AERONET site.