Evaluation of VIIRS, GOCI, and MODIS Collection 6 AOD retrievals against ground sunphotometer measurements over East Asia
Monday, 15 December 2014
Persistent high aerosol loadings together with extremely high population density have raised serious air quality and public health concerns in most urban centers in East Asia. Recently, satellite retrieved Aerosol Optical Depth (AOD) has become a powerful tool to better characterize aerosol patterns in space and time. Using data from the Distributed Regional Aerosol Gridded Observation Networks (DRAGON) and the Aerosol Robobotic Network (AERONET) (over 40 permanent and temporary sites), as well as handheld sunphotometers, we evaluated the AOD products from the Visible Infrared Imaging Radiometer Suite (VIIRS), the Geostationary Ocean Color Imager (GOCI), and the Moderate Resolution Imaging Spectroradiometer (MODIS) (Collection 6) in East Asia in 2012 and 2013. During the study period, GOCI AOD provides the best temporal coverage (80%), followed by VIIRS Intermediate Product (IP) (75%), VIIRS Environmental Data Record (EDR) (59%), and MODIS C6 3 km AOD (27%). The mean bias of VIIRS EDR, VIIRS IP, GOCI, and MODIS C6 3 km AOD are 0.08, 0.25, 0.01, and 0.15, respectively. When compared with ground observations, 56% of EDR, 27% of IP, 51% of GOCI, and 47% of MODIS C6 3 km AOD fall within the global expected error (EE) range of MODIS over land (±0.05±0.15AOD). EDR, IP, and MODIS C6 3km aerosol products perform better in rural areas, with a bias less than half of that in urban areas and more than 80% more retrievals falling within EE relative to in urban areas. Over Metro Beijing, comparing with AOD measured by handheld sunphotometers, 51% of VIIRS EDR AOD, 31% of VIIRS IP AOD, 33% of GOCI AOD, and 17% of MODIS AOD fall within the MODIS EE.
Keywords – Aerosol Optical Depth; VIIRS; MODIS; GOCI; AERONET; DRAGON