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

Abstract

The second-generation MODIS aerosol retrieval (Collection 005) from EOS- Aqua (2002–2005) was evaluated using ground-based AERONET measurements at Kanpur (26.45°N, 80.35°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 μm and 0.55 μm and 60% of the retrievals at 0.66 μm wavelength in the new version fall within the pre-launch uncertainty (Δτ = ±0.05 ± 0.15τ, where τ is AOD) with better correlation (R2 ∼ 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.