●●●●D●●●●●●● 14Synchrotron radiation is generated when an electron traveling at the speed of light is forced to change direction by a magnetic field. Synchrotron radiation is called “dream light” because it is not only powerful but also includes light of various wavelengths. The institute promotes advanced materials science and emerging interdisciplinary fields using synchrotron radiation.o you know what the term “remote sensing” stands for? It refers to “non-contact measurement.” To put it simply, it involves using cameras on satellites, drones or balloons to capture images of objects on the ground and create maps. My research interests center around applying remote sensing to monitor aquatic environments, especially oceans and lakes. In recent years, with higher water temperatures and water levels due to global warming, issues affecting fishing and daily life are becoming more frequent and serious. In such a situation, remote sensing is expected to play an important role in monitoring the health of water bodies.I first encountered this research subject as a university student, when my professor proposed a project to me. Its objective was to demonstrate a hypothesis about Lake Shinji in Shimane Prefecture, famous for its □□□□□□□ clams, using satellite data. The hypothesis stated that the areas of the lake where the clams live have clearer water than other parts of the lake. It may sound surprising, but it turned out to be true. □□□□□□□ clams filter suspended particles from the water to obtain nutrients, which means that the water above clam beds tends to be clearer. But how could we measure this "clarity," that is, the absence of murkiness, which actually indicates the distribution of chlorophyll? Some satellites are equipped with ocean color sensors specifically designed to measure chlorophyll. Chlorophyll absorbs blue and red light and reflects only green, and by measuring the amount of light absorbed, satellites can estimate chlorophyll levels. However, the problem with this method was that most ocean color sensors have a resolution of about 1 km. Lake Shinji, which is roughly 20 km long and 5 km wide, with clam beds only about 1 km from the shore, was too small for these sensors to capture clearly. To counter this problem, I devised a method to use higher-resolution satellite images, mainly the French SPOT satellite with a 20-meter spatial resolution, to measure chlorophyll in the lake. I thereby demonstrated that the waters where □□□□□□□ clams live tend to be clearer, on average, than other parts of the lake. This work earned me my doctorate.Since this project, I have been thoroughly enthralled by remote sensing. Even since becoming a university professor, I have still been immersing myself in mapping the environments of oceans and lakes using this technology. At present, I am using satellites, drones, and balloons (Photo 1), expanding my research to include mapping coral reefs (Photo 2) and seagrass beds, not just to measure chlorophyll. At the end of each research project, we always need to conduct physical validation from a boat. So my lab regularly engages in marine observation (Photo 3). Fortunately, Hiroshima University provides easy access to research vessels and has numer-ous labs whose members are willing to collabo-rate with us. These ideal settings have allowed us to generate many new research projects. This combination of the cutting-edge technolo-gy of satellite remote sensing and traditional boat-based fieldwork has earned my research a solid reputation. As a result, courses and research in this field are extremely popular with students. Together with these students passionate about measuring and diagnosing water environments, I am committed to continuing my research and exploring new frontiers.Satellite visible (background) and thermal (above) images of Hiroshima City indicating higher ground temperatures along the Ota River and its branchesPhoto 3: Boat-based fieldwork to validate in detail satellite-cap-tured ocean colors and temperaturesPhoto 1: Capturing water surface images using a balloon for seagrass bed mappingPhoto 2: Indoor experiment in an aquarium for satellite coral reef mapping*HiSIM (Hiroshima-University STARC IGFET Model) is a transistor model used in circuit design that has been developed by Hiroshima University in collaboration with the Semiconductor Technology Academic Research Center (STARC).Aquatic environment remote sensingProfessorGraduate Schoolof Advanced Science and EngineeringSchool of EngineeringResearch interestsAcademic-Environment Social Governance Science and Technology Research CenterTown ＆ Gown Institute of Innovation for the FutureHiroshima University PSI GMP CenterThe Institute for Diversity & InclusionSeto Inland Sea Carbon-neutral Research CenterGlobal Campus Institute, Hiroshima UniversityCenter for Brain, Mind and KANSEI Sciences Research Hiroshima University Genome Editing Innovation Center Hiroshima University Digital Monozukuri (Manufacturing) Education and Research CenterEducation and Research Center for Artificial Intelligence and Data InnovationThe IDEC InstituteResearch Institute for Synchrotron Radiation ScienceUniversity of World-wide Repute and Splendor for Years into the Future ▼▼▼Researchers Leading the WorldNational Joint Usage FacilitySAKUNO YujiExamining the wellness of oceans and lakeswith satellites, drones, and balloons supporting world-class research
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