Validation of MODIS Fine Mode Retrievals Over Ocean

The MODIS (MODerate Resolution Imaging Spectroradiometer) algorithm can accurately partition aerosol into fine and coarse modes for aerosol optical depths greater than 0.1. The algorithm is validated against both AERONET sky and sun measurements using a co-located data set encompassing four years of data from 30 sites. MODIS slightly overestimates fine fraction in dust dominated regimes and may underestimate in pollution and smoke dominated conditions for individual measurements. The accuracy of monthly mean retrievals improves significantly showing very little offset and almost completely eliminating the trend seen in the individual measurements. These results show that MODIS is an excellent tool for determining aerosol types and sources especially for climate studies.