Assessment of second-generation MODIS aerosol retrieval (Collection 005) at Kanpur, India

The second-generation MODIS aerosol retrieval ( Collection 005) from EOS- Aqua (2002-2005) was evaluated using ground-based AERONET measurements at Kanpur (26.45 degrees N, 80.35 degrees E) northern India. We found that the aerosol optical depth (AOD) retrievals are more accurate compared to that of previous retrieval ( Collection 004). About 70% of the total retrievals at 0.47 mu m and 0.55 mu m and 60% of the retrievals at 0.66 mu m wavelength in the new version fall within the pre-launch uncertainty (Delta tau = +/-0.05 +/- 0.15 tau, where tau is AOD) with better correlation (R-2 similar to 0.83) at all three wavelengths. However, MODIS still tends to over-estimate AOD for a few retrievals in the presence of dust aerosols. The error in the fine-dominated AOD was large for most retrievals in the C005. However, the fine-dominated AOD of Collection 004 was better correlated with the equivalent AERONET data. This suggests that the fine-dominated AOD retrievals need to be re-examined further.