Validation of high‐resolution MAIAC aerosol product over South America. Issue 14 (26th July 2017)

• Record Type: Journal Article
• Authors: Martins, V. S.; Lyapustin, A.; de Carvalho, L. A. S.; Barbosa, C. C. F.; Novo, E. M. L. M.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 14(2017)
• Page Start: 7537
• Page End: 7559
• Publication Date: 2017-07-26
• Subjects: MODIS‐MAIAC -- South America -- aerosol optical depth (AOD) -- columnar water vapor (CWV) -- AERONET; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1002/2016JD026301
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Multiangle Implementation of Atmospheric Correction (MAIAC) is a new Moderate Resolution Imaging Spectroradiometer (MODIS) algorithm that combines time series approach and image processing to derive surface reflectance and atmosphere products, such as aerosol optical depth (AOD) and columnar water vapor (CWV). The quality assessment of MAIAC AOD at 1 km resolution is still lacking across South America. In the present study, critical assessment of MAIAC AOD550 was performed using ground‐truth data from 19 Aerosol Robotic Network (AERONET) sites over South America. Additionally, we validated the MAIAC CWV retrievals using the same AERONET sites. In general, MAIAC AOD Terra/Aqua retrievals show high agreement with ground‐based measurements, with a correlation coefficient ( R ) close to unity ( R Terra :0.956 and R Aqua : 0.949). MAIAC accuracy depends on the surface properties and comparisons revealed high confidence retrievals over cropland, forest, savanna, and grassland covers, where more than 2/3 (~66%) of retrievals are within the expected error (EE = ±(0.05 + 0.05 × AOD)) and R exceeding 0.86. However, AOD retrievals over bright surfaces show lower correlation than those over vegetated areas. Both MAIAC Terra and Aqua retrievals are similarly comparable to AERONET AOD over the MODIS lifetime (small bias offset ~0.006). Additionally, MAIAC CWV presents quantitative information with R ~ 0.97 and more than 70% of retrievals within error (±15%). Nonetheless, the time series validation shows an upward bias trend in CWV Terra retrievals and systematic negative bias for CWV Aqua. These results contribute to a comprehensive evaluation of MAIAC AOD retrievals as a new atmospheric product for future aerosol studies over South America. Key Points: Comprehensive validation of aerosol optical depth (AOD) at 550 nm from MAIAC Terra and Aqua according to land cover types over South America Accuracy of MAIAC AOD550 retrievals varies as function of land cover type, AOD magnitude, and climatological seasons in South America MAIAC AOD550 retrievals are stable over the MODIS Terra and Aqua mission