GOCI Yonsei Aerosol Retrieval Version 2 Products: Long-Term Analysis during 2011-2017

GOCI (the Geostationary Ocean Color Imager), the world first and unique ocean color imager in geostationary earth orbit, has been observed East Asia since 2011 so that hourly data in the daytime have been archived over 7 years. Utilization of multi-channel measurements in the visible to near-infrared range with high spatial resolution enable the retrieval of accurate aerosol optical properties (AOPs), similar with current polar-orbiting sensors such as MODIS and VIIRS. Recently updated GOCI Yonsei aerosol retrieval version 2 algorithm provide improved aerosol optical depth (AOD) with estimated uncertainties and other optical properties as near-real-time (NRT). This improvement is highly desirable for use with air quality monitoring and data assimilation with air-quality forecasting models, particularly when rapid diurnal variations and transboundary transport are significant. Based on the long-term measurement records, climatological database of GOCI AOPs can be constructed as higher spatial resolution compared to classical 1°×1° longitude-latitude grid daily/monthly data from MODIS. This is because the number of samplings at same pixel can be higher in GOCI than LEO measurements due to multiple observations during a day. Also, it results in better representative daily-mean AOD, and it has broader coverage than LEO measurements because the possibility to avoid cloud contamination increases during a day. Constructed long-term GOCI AOPs are analyzed and compared with other LEO measurements and ground-based AERONET measurement.