10:45 AM - 12:15 PM
[HTT17-P09] Assessments of GOSAT cloud detections using multiple satellite sensors and data qualities of CO2 profile data in cloud-contaminated scenes
Keywords:cloud detection, GOSAT, GHG retrieval
Before retrieving greenhouse gas concentrations from spectra of the Thermal and Near Infrared Sensor for Carbon Observation (TANSO)−Fourier Transform Spectrometer (FTS) on board Greenhouse Gases Observing Satellite (GOSAT), cloud contaminations in the field of views (FOVs) of TANSO−FTS have been judged by TANSO−Cloud and Aerosol Imager (CAI) and the short-wave infrared (SWIR) band of TANSO−FTS in the daytime and by the thermal infrared (TIR) band of TANSO−FTS in the nighttime. We developed a method for detecting cloud contaminations in the FOVs of TANSO−FTS using reflectance and brightness temperature data of coincident measurements of the Advanced Himawari Imager (AHI) on board Himawari−8 and validated the GOSAT cloud judgements [Saitoh and Kitamura, RSSJ, 2021]. In addition to the AHI data, we also used cloud layer products of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) for further assessments of the GOSAT cloud detections.
From comparisons of cloud detection results by the TIR band of TANSO−FTS with the cloud layer products of CALIOP/CALIPSO, we found that the TIR cloud detections showed no clear differences in their accuracy between day and night scenes and that they missed low level clouds and optically thin clouds. We then compared observed radiances of the TANSO−FTS TIR band between clear-sky and cloud-contaminated scenes based on the comparisons with CALIOP, and found that the radiances in cloud-contaminated scenes were clearly lower than those in clear-sky scenes; this suggests that TANSO−FTS TIR GHG observations could be degraded especially in the nighttime and the data quality of the retrieved GHG concentrations should be carefully evaluated.
From comparisons of cloud detection results by the TIR band of TANSO−FTS with the cloud layer products of CALIOP/CALIPSO, we found that the TIR cloud detections showed no clear differences in their accuracy between day and night scenes and that they missed low level clouds and optically thin clouds. We then compared observed radiances of the TANSO−FTS TIR band between clear-sky and cloud-contaminated scenes based on the comparisons with CALIOP, and found that the radiances in cloud-contaminated scenes were clearly lower than those in clear-sky scenes; this suggests that TANSO−FTS TIR GHG observations could be degraded especially in the nighttime and the data quality of the retrieved GHG concentrations should be carefully evaluated.