Validation of MODIS C6.1 and MERRA-2 AOD Using AERONET Observations: A Comparative Study over Turkey

• Published in: Atmosphere
• Main Authors: Midyan Aldabash, Filiz Bektas Balcik, Paul Glantz
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: aerosol optical depth; MODIS Terra-Aqua; MERRA-2; RH%; AERONET; validation; Meteorology. Climatology; QC851-999; Merra; Aerosol Robotic Network
• Online Access: https://doi.org/10.3390/atmos11090905; https://doaj.org/article/45fbb5540296425daa9d8ba848a18c31

This study validated MODIS (Moderate Resolution Imaging Spectroradiometer) of the National Aeronautics and Space Agency, USA, Aqua and Terra Collection 6.1, and MERRA-2 (Modern-ERA Retrospective Analysis for Research and Application) Version 2 of aerosol optical depth (AOD) at 550 nm against AERONET (Aerosol Robotic Network) ground-based sunphotometer observations over Turkey. AERONET AOD data were collected from three sites during the period between 2013 and 2017. Regression analysis showed that overall, seasonally and daily statistics of MODIS are better than MERRA-2 by the mean of coefficient of determination (R 2 ), mean absolute error (MAE), and relative root mean square deviation (RMSD rel ). MODIS combined Terra/Aqua AOD and MERRA-2 AOD corresponding to morning and noon hours resulted in better results than individual sub datasets. A clear annual cycle in AOD was detected by the three platforms. However, overall, MODIS and MERRA-2 tend to overestimate and underestimate AOD, respectively, in comparison with AERONET. MODIS showed higher efficiency in detecting extreme events than MERRA-2. There was no clear relation found between the accuracy in MODIS/MERRA-2 AOD and surface relative humidity (RH).