17:15 〜 18:45
[PEM12-P06] A comparison of polar mesospheric cloud observations by Himawari-8/AHI and Himawari-9/AHI
キーワード：極中間圏雲、夜光雲、ひまわり8号 / AHI、ひまわり9号 / AHI、長期観測
Polar mesospheric clouds (PMCs), also knwon as noctilucent clouds (NLCs), consist of water-ice particles that can be formed in summer around the mesopause region, mainly at high latitudes. The formation and loss of water-ice particles are considered to be sensitive to mesospheric conditions such as atmospheric temperature, mixing ratio of water vapour, etc. Thus, observations of PMCs/NLCs can be a useful diagnosis to understand both dynamics and chemistry in the Earth's mesosphere. Various methods have been used to observe PMCs, including ground-based optical imaging and lidar systems. These ground-based methods provide local observations with exceptional spatial and temporal resolutions, but are limited by tropospheric weather conditions. In contrast, PMC observations from space are valuable for more continuous and larger spatial coverage observations with lower spatial and temporal resolutions.
To advance long-term PMC observations from space, a PMC detection method was developed for application to the full-disk images obtained by the Advanced Himawari Imager (AHI) onboard the Japanese geostationary-Earth-orbit (GEO) meteorological satellite Himawari-8. It was reported that the detection sensitivity of PMC by Himawari-8/AHI is comparable to that of Cloud Imaging and Particle Size (CIPS) onboard Aeronomy of Ice in the Mesosphere (AIM). Himawari-8/AHI completed its regular operation on 13 December 2022, and Himawari-9/AHI is now in operation. Himawari-9/AHI is an identical instrument to Himawari-8/AHI. It is expected that Himawari-9/AHI will provide PMC observations comparable to those of Himawari-8/AHI.
The aim of this study is to start PMC observations with Himawari-9/AHI and to evaluate its capabilities by comparing Himawari-8/AHI and Himawari-9/AHI PMC data. We analyzed PMC data obtained from 1 to 13 December 2022, during which simultaneous PMC observations were successfully carried out by Himawari-8/AHI and Himawari-9/AHI in the early summer of the Southern Hemisphere. The Himawari-9/AHI PMC data were obtained using the same PMC detection method as that for Himawari-8/AHI. Comparisons were made between the PMC data from Himawari-8/AHI and Himawari-9/AHI. The results showed that 99.8% of the PMC detection results from Himawari-9/AHI agreed with those from Himawari-8/AHI. As for the PMC height data, 98.3% of the data showed agreement within ±1 km. Thus, PMC observation results by Himawari-9/AHI were well-consistent with those by Himawari-8/AHI, and PMC observations by Himawari-9/AHI have successfully started without major problems. In the future, a longer PMC dataset could be provided by combining Himawari-8/AHI and Himawari-9/AHI. This would contribute to investigations on long-term PMC variations.
To advance long-term PMC observations from space, a PMC detection method was developed for application to the full-disk images obtained by the Advanced Himawari Imager (AHI) onboard the Japanese geostationary-Earth-orbit (GEO) meteorological satellite Himawari-8. It was reported that the detection sensitivity of PMC by Himawari-8/AHI is comparable to that of Cloud Imaging and Particle Size (CIPS) onboard Aeronomy of Ice in the Mesosphere (AIM). Himawari-8/AHI completed its regular operation on 13 December 2022, and Himawari-9/AHI is now in operation. Himawari-9/AHI is an identical instrument to Himawari-8/AHI. It is expected that Himawari-9/AHI will provide PMC observations comparable to those of Himawari-8/AHI.
The aim of this study is to start PMC observations with Himawari-9/AHI and to evaluate its capabilities by comparing Himawari-8/AHI and Himawari-9/AHI PMC data. We analyzed PMC data obtained from 1 to 13 December 2022, during which simultaneous PMC observations were successfully carried out by Himawari-8/AHI and Himawari-9/AHI in the early summer of the Southern Hemisphere. The Himawari-9/AHI PMC data were obtained using the same PMC detection method as that for Himawari-8/AHI. Comparisons were made between the PMC data from Himawari-8/AHI and Himawari-9/AHI. The results showed that 99.8% of the PMC detection results from Himawari-9/AHI agreed with those from Himawari-8/AHI. As for the PMC height data, 98.3% of the data showed agreement within ±1 km. Thus, PMC observation results by Himawari-9/AHI were well-consistent with those by Himawari-8/AHI, and PMC observations by Himawari-9/AHI have successfully started without major problems. In the future, a longer PMC dataset could be provided by combining Himawari-8/AHI and Himawari-9/AHI. This would contribute to investigations on long-term PMC variations.