First results of cloud retrieval from the Geostationary Environmental Monitoring Spectrometer

This paper introduces a cloud retrieval algorithm for the Geostationary Environmental Monitoring Spectrometer (GEMS), the first environmental geostationary orbit satellite, and validates its cloud products by comparing them with those produced by other instruments (OMI, TROPOMI, AMI, and CALIOP). The GEMS cloud products are corrected for the impact of clouds on the retrieval of atmospheric components using the O2-O2 absorption band to retrieve the effective cloud fraction and cloud centroid pressure. The performance of the GEMS cloud retrieval algorithm was similar to that of the OMI. We analyzed the cloud retrieval characteristics for air pollution, typhoons, and sea fog in the East Asian region to evaluate whether GEMS cloud data can accurately represent various cloud features. Also, we evaluated the accuracy of the cloud retrieval algorithm through monthly validation for 2 years. The validation results provide a basis for future improvements of the GEMS cloud retrieval algorithm.