Validation of MODIS aerosol optical depth retrieval over land

Aerosol optical depths (τ a ) are derived operationally for the first time from the MODIS (Moderate Resolution Imaging Spectroradiometer) measurements over vegetated and partially vegetated land at 0.47 and 0.66 μm wavelengths. The extensive validation made during July – September 2000 encompasses 315 co‐located τ a in space and time derived by MODIS and AERONET (Aerosol Robotic Network) from more than 30 AERONET sites. The lack of AERONET measurements in East Asia, India and Australia makes this validation unavailable for those regions. The MODIS aerosol retrievals, except in coastal zones, are found within the retrieval errors of Δτ a = ±0.05 ±0.2 τ a . The root mean square (RMS) errors are ≤ 0.1 in the…