Publications

Zhang, M; Zhang, L; He, QQ; Yuan, YB (2022). Evaluation of the MODIS Collection 6.1 3 km aerosol optical depth product over China. ATMOSPHERIC ENVIRONMENT, 273, 118970.

Abstract
The Moderate Resolution Imaging Spectroradiometer (MODIS) 3 km aerosol product was released to resolve fine aerosol features and provide regional high-resolution aerosol distributions required by the air quality community. It has been publicly available since the Collection 6 (C6) release. In the Collection 6.1 (C6.1) release, a new surface parameterization scheme has been introduced to improve the accuracy of retrieved aerosol optical depth (AOD) over urban surfaces, whereas few detailed evaluations have been conducted. In the present study, we comprehensively evaluated the MODIS C6.1 3 km (C6.1_3km) AOD product over China for the 2001-2017 period. The C6.1_3km product was validated against Aerosol Robotic Network (AERONET) data and compared with the C6 3 km (C6_3km) and C6.1 10 km (C6.1_10km) products. The spatial averaging technique was used to generate MODIS-AERONET collocations for C6_3km and C6.1_3km, whereas the single pixel collocation technique was used for comparing the C6.1_3km and C6.1_10km retrievals. Different collocation techniques were used because we found that the single pixel collocation technique was more suitable for evaluating aerosol products of different spatial resolutions over urban areas. Results indicated that the C6.1_3km product outperformed the C6_3km product over urban areas because of the new C6.1 surface parameterization scheme, while the upstream changes implemented in C6.1 have minor effects on the improvement. The C6.1_3km product showed a similar performance as compared to the C6.1_10km product, which indicated that the C6.1 surface scheme originally designed on a 10 km scale performed equally well at the 3 km spatial resolution. However, the evaluation statistics also indicated that an overestimation of AOD values over urban areas still existed in the C6.1_3km aerosol product. Therefore, refinement of the DT algorithm is required to further improve the C6.1_3km product for air quality studies over urban areas in China.

DOI:
10.1016/j.atmosenv.2022.118970

ISSN:
1873-2844