Validation of the above-cloud aerosol optical depth retrieved using the "color ratio" method applied to MODIS cloudy-sky measurements against airborne direct measurements made by NASA’s AATS and 4STAR sun photometers during SAFARI-2000, ACE-ASIA 2001, and SEAC4RS 2013 reveals a good level of agreement (difference < 0.1), in which most matchups are found be constrained within the estimated uncertainties associated with the MODIS retrievals (-10 % to +50 %).