2022 Fiscal Year Final Research Report

Observation of water vapor, wave height, and sea level in the East China Sea using ship-borne GNSS measurements

Research Project

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Project/Area Number	20H02420
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 25030:Disaster prevention engineering-related
Research Institution	Japan, Meteorological Research Institute
Principal Investigator	Shoji Yoshinori 気象庁気象研究所, 気象観測研究部, 研究官 (70354446)
Co-Investigator(Kenkyū-buntansha)	津田敏隆京都大学, 生存圏研究所, 研究員 (30115886) 矢吹正教京都大学, 生存圏研究所, 特定研究員 (80390590)
Project Period (FY)	2020-04-01 – 2023-03-31
Keywords	海上水蒸気観測 / GNSS / 移動体測位
Outline of Final Research Achievements	It was found that the vertical coordinate solution of Kinematic Precise Point Positioning has biases that depend on time length of batch processing, solution update time interval, and time constraint of atmospheric delay, which are closely related to the estimation error of GNSS derived precipitable water vapor (PWV). By conducting analysis tests while modifying the aforementioned three conditions, we were able to mitigate two issues highlighted in a previous study: (1) unnatural time variation of GNSS derived PWV and (2) the tendency of GNSS derived PWV to underestimate, which became more pronounced in high PWV environments. The analysis method obtained in this project was adopted in the implementation of ship-based GNSS system carried out by the Japan Meteorological Agency in FY2021 and FY2022. Furthermore, it was found that the analysis method obtained in this work could be a promising observation technique for estimating significant wave heights and secondary undulations.
Free Research Field	気象学
Academic Significance and Societal Importance of the Research Achievements	精密衛星測位の一手法である精密単独測位は、全球で適用可能な測位手法である。移動体の鉛直座標精度評価は十分になされていない。本研究の結果、固定点の測位解析に比べて誤差が大きく、また解析手法のわずかな違いが大きく影響することが判明した。GNSSを用いた大気計測の精度は、測位精度と不可分な関係にあり、本研究で得られた知見は、衛星測地学分野への問題提起にとどまらず、課題解決に向けた衛星測地分野と大気研究分野の学際協力の必要性を提起する。本研究の成果は気象庁の船舶搭載GNSSによる海上水蒸気観測に採用された。豪雨の機構解明や予測精度改善を通じて災害軽減に資することが期待される。