10:45 AM - 11:00 AM
[MSD40-07] Role of Japan on polarization observations from space
The color composite images from Himawari-8/AHI (Advanced Himawari Imager) and SGLI (Second-Generation GLobal imager) are presented in Fig.1a and 1b, respectively. The images by Himawari have become an integral part of our daily lives. The image by SGLI visualizes the heavy smoke over large scale forest fires in the western Canada on Aug. 14, 2018. It is well known that large-scale wild fires have occurred worldwide since 2018 owing to global warming and climate change.
The so-called imagers currently on board the Japanese satellite are AHI, SGLI and CAI-2. The AHI mounts on the geostationary meteorological satellite Himawari-8 launched on October 7, 2014. The functions and specifications of AHI are notably improved. AHI is a 16 channel multispectral imager to capture visible light and infrared images of the Asia-Pacific region, then AHI contributes to not only weather prediction but also environmental monitoring. The SGLI on board GCOM-C launched on December 23, 2017 contains 19 channels from near-UV (380 nm) to infrared. The CAI (Cloud and Aerosol Imager)-2 on the GOSAT-2 launched on October 29, 2018 is a push-broom radiometer with 10 channels in the spectral ranges from ultra violet to short wavelength infrared for the observation of aerosols and clouds optical properties and for monitoring of air pollution. These imagers not only have the capability of high resolution at multiple wavelengths, but also each has its own unique capability and makes a great contribution to the global environment by utilizing the excellent features of AHI's high temporal resolution, SGLI's polarization information, and CAI-2's two-way observation. It is clear that these sensors are not just for capturing the satellite images that the word "imager" implies, but it is also clear that the information that satellite images directly appeal to intuitively is large and strong.
The usefulness and important role of imagers in atmospheric environment analysis will be partly introduced, focusing on the SGLI that our group has been involved in. The SGLI encompasses two polarization channels PL1 (674 nm) and PL2 (869 nm) with 1 km instantaneous field-of-view (IFOV). Note that this polarization measurement is the smallest resolution obtained to date. As shown in Figure 2, the sensitivities of the non-PL band (674) (b) and PL band (674) (c) are different. This is likely because the radiance channel considers the observations of darker targets, such as vegetation and land cover. Thus, the black area exists in color composite image (a). The dark yellow color spreading in the upper central region of the image (a) denotes the smoke caused by the wild fire events owing to the near-UV band (380). Further, the swaths of both images (b) and (c) are different because of differences in observation angles, wherein the radiance observation telescope observes downward, and the polarization telescope observes at 45° oblique. In other words, two-directional observation is available, and geometrical information is obtained.
This is just one example, but it shows the effectiveness of the complementarity between the polarization information and the non-polarized radiance measurements from the SGLI for biomass burning aerosol retrieval. In this way, the SGLI observables have various possibilities. The technology and experience of multi-wavelength polarization sensors cultivated by SGLI should be inherited. Even if the revolutionary aerosol and cloud sensor 3MI; muti-viewing, -channel, -polarization imager: will fly to space on the MetOp-SGA satellite in 2022, the successor of SGLI is still very valuable. There's no substitute for sustainability.
The so-called imagers currently on board the Japanese satellite are AHI, SGLI and CAI-2. The AHI mounts on the geostationary meteorological satellite Himawari-8 launched on October 7, 2014. The functions and specifications of AHI are notably improved. AHI is a 16 channel multispectral imager to capture visible light and infrared images of the Asia-Pacific region, then AHI contributes to not only weather prediction but also environmental monitoring. The SGLI on board GCOM-C launched on December 23, 2017 contains 19 channels from near-UV (380 nm) to infrared. The CAI (Cloud and Aerosol Imager)-2 on the GOSAT-2 launched on October 29, 2018 is a push-broom radiometer with 10 channels in the spectral ranges from ultra violet to short wavelength infrared for the observation of aerosols and clouds optical properties and for monitoring of air pollution. These imagers not only have the capability of high resolution at multiple wavelengths, but also each has its own unique capability and makes a great contribution to the global environment by utilizing the excellent features of AHI's high temporal resolution, SGLI's polarization information, and CAI-2's two-way observation. It is clear that these sensors are not just for capturing the satellite images that the word "imager" implies, but it is also clear that the information that satellite images directly appeal to intuitively is large and strong.
The usefulness and important role of imagers in atmospheric environment analysis will be partly introduced, focusing on the SGLI that our group has been involved in. The SGLI encompasses two polarization channels PL1 (674 nm) and PL2 (869 nm) with 1 km instantaneous field-of-view (IFOV). Note that this polarization measurement is the smallest resolution obtained to date. As shown in Figure 2, the sensitivities of the non-PL band (674) (b) and PL band (674) (c) are different. This is likely because the radiance channel considers the observations of darker targets, such as vegetation and land cover. Thus, the black area exists in color composite image (a). The dark yellow color spreading in the upper central region of the image (a) denotes the smoke caused by the wild fire events owing to the near-UV band (380). Further, the swaths of both images (b) and (c) are different because of differences in observation angles, wherein the radiance observation telescope observes downward, and the polarization telescope observes at 45° oblique. In other words, two-directional observation is available, and geometrical information is obtained.
This is just one example, but it shows the effectiveness of the complementarity between the polarization information and the non-polarized radiance measurements from the SGLI for biomass burning aerosol retrieval. In this way, the SGLI observables have various possibilities. The technology and experience of multi-wavelength polarization sensors cultivated by SGLI should be inherited. Even if the revolutionary aerosol and cloud sensor 3MI; muti-viewing, -channel, -polarization imager: will fly to space on the MetOp-SGA satellite in 2022, the successor of SGLI is still very valuable. There's no substitute for sustainability.