Evaluation of GOCI Aerosol Products over East Asia

Abstract:

The Geostationary Ocean Color Imager (GOCI) is a one of sensors onboard Communication, Ocean, and Meteorological Satellite (COMS) launched in June 2010. Located at geostationary orbit, GOCI can provide hourly images, total 8 times in daytime covering East Asia over 2500 km × 2500 km centered at 130°E and 36°N with 500 m spatial resolution.  Using 8 channels in visible and near-infrared from 412 to 865 nm of GOCI both in high temporal and spatial resolution, the GOCI aerosol property retrieval algorithm has been developed and updated. Latest GOCI aerosol products consist of aerosol optical depth (AOD) and fine-mode fraction (FMF) at 550nm, single scattering albedo (SSA) at 440nm, Angstrom exponent (AE) between 440-870nm, and aerosol type according to FMF and SSA.

In this study, we evaluated the accuracy of GOCI aerosol products using ground-based AERONET Level 2.0 products from total 14 East Asia sites and satellite-based MODIS-Aqua aerosol C6 products. The period of assessment is 3 years from March 2011 to February 2014. Comparison results show that a correlation coefficient between the AODs at 550 nm of AERONET and GOCI  is 0.922, and RMSE is 0.179 over total sites with regression equation of AOD (GOCI) = 0.959 * AOD (AERONET) - 0.027. Difference of GOCI AOD and the AERONET is analyzed according to scattering angle, surface reflectance, and season. Validation of AE shows high correlation in spring season. It also shows good agreement with MODIS-Aqua aerosol products. Preliminary results show that the correlation coefficient and RMSE between GOCI and MODIS DT AOD are 0.826 and 0.196, respectively. With MODIS DB AOD, these values are 0.776 and 0.335, respectively. The trend of 3-year GOCI AOD over East Asia shows decreasing except for Korea peninsula. During Feb, 2014, highest AOD was detected from GOCI and AERONET over the Korea peninsula.