2021 Fiscal Year Final Research Report

A challenge to develop GNSS buoy system for high-functional tsunami monitoring and continuous observation of ocean-bottom crustal movements

Research Project

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Project/Area Number	16H06310
Research Category	Grant-in-Aid for Scientific Research (S)
Allocation Type	Single-year Grants
Research Field	Natural disaster / Disaster prevention science
Research Institution	Taisho University (2020-2021) Hot Springs Research Institute of Kanagawa Prefecture (2018-2019) The University of Tokyo (2016-2017)
Principal Investigator	Kato Teruyuki 大正大学, 地域構想研究所, 特命教授 (80134633)
Co-Investigator(Kenkyū-buntansha)	寺田幸博高知工業高等専門学校, その他部局等, 客員教授 (30442479) 田所敬一名古屋大学, 環境学研究科, 准教授 (70324390) 二村彰弓削商船高等専門学校, 商船学科, 教授 (90332080)
Project Period (FY)	2016-05-31 – 2021-03-31
Keywords	GNSSブイ / 津波防災 / 海底地殻変動連続観測 / 衛星通信技術
Outline of Final Research Achievements	A new GNSS buoy system was developed for deploying at a far offshore. For this purpose, we used so-called PPP-AR method together with satellite communication link for sending precise orbits for PPP-AR and sending back the obtained coordinates of the buoy. The experiment at a fishery buoy off Cape Ashizuri, Kochi, Japan, showed that the sea-level change can be monitored in a few centimeter accuracy in real-time. We also evaluated the effects of phasing due to tilting of the buoy and found that it can be expressed by a log-normal distribution based on a buoy data. In addition, a new effective method of data uplink of the buoy data to a communication satellite was developed. On the challenge for the continuous observation of the ocean-bottom crustal movements, a new processing algorithm was developed and it was implemented in the buoy system. The results of the several months of experiment showed that the array position at the sea-bottom can be estimated with a few centimeters accuracy.
Free Research Field	固体地球物理学
Academic Significance and Societal Importance of the Research Achievements	GNSSブイを実質上距離制限の不要な遠洋で運用し、海面高を即時的かつ数cm精度で監視できることを実証した。これにより津波の早期発見と住民の避難に一層役立てられることが示された。また、海底地殻変動を高頻度かつ数cm精度で推定することができ、海底での短期的な変動をも捉えることができることを示した。これらに加え，衛星通信に関しても新たな手法が提案され、海洋での広範な利用が期待できる。海洋GNSSブイは、これらの他にも気象学や電離層研究にも用いることができるため、多目的の総合的な防災システムとして防災への貢献が期待できるばかりでなく、基礎的な地球科学の研究にも革新的なデータを提供できることを示した。