4. GNSS-A observation data in GARPOS format obtained at the SGO-A sites

DOI: https://doi.org/10.57553/2024001
Authors: Geodesy and Geophysics Office, Coastal Surveys Division, Hydrographic and Oceanographic Department, Japan Coast Guard
Abstract: This is a dataset created by organizing and integrating following datas for analysis by the GNSS-A station location solver GARPOS (Watanabe et al., 2020, Front. Earth Sci.). The data is consist of four data types; the net round trip travel time of acoustic ranging, ship GNSS positioning solution, ship sway data and undersea sound speed profile. The data analysis method is in the research and development stage, so the data may be updated due to improvements.
Original site: Hydrographic and Oceanographic Department, Japan Coast Guard https://www1.kaiho.mlit.go.jp/chikaku/kaitei/sgs/gnss-a_obsdata_e.html
Persistent link: WARP https://warp.ndl.go.jp/info:ndljp/pid/13157427/www1.kaiho.mlit.go.jp/chikaku/kaitei/sgs/gnss-a_obsdata.html 2024.01.05
Method: The acoustic round trip travel time is calculated using the algorithm proposed by Tomiyama (2003, Marine Information Department Technical Report). from the obtained acoustic data. We use the net round trip travel time obtained by this algorithm minus the response time specific to the seafloor transponder. The GNSS positioning solution is obtains from 2 Hz GNSS observation data acquired by a GNSS antenna on the ship and the IGS final ephemeris, etc., and it is calculated by kinematic precision independent positioning using RTKLIB (Takasu, 2013), with the influence of solid earth tides removed. The ship sway data is consists of roll, pitch, and heading data acquired at 50 or 100 Hz. The GNSS positioning solution and the ship sway data at the time of transmission and reception of the acoustic signal are obtained from the above data by Akima interpolation and linear interpolation, respectively. The underwater sound speed profile is expressed as a piecewise line system function by averaging the water temperature and salinity profiles of multiple XBTs and XCTDs dropped during observation and converting it to sound speed using the empirical rule of Del Grosso (1974).
Keywords: GNSS-A, GNSS-A methodology
Observer : S/V Meiyo S/V Kaiyo S/V Takuyo S/V Shoyo S/V Heiyo S/V Koyo
Correspondence: Geodesy and Geophysics Office, Coastal Surveys Division, Hydrographic and Oceanographic Department, Japan Coast Guard
Resource Type: Dataset
Date: 2008~
GeoLocation: Pacific coast from the Japan Trench to the Nankai Trough
IsDescribedBy : Frontiers in Earth Science https://doi.org/10.3389/feart.2020.597532
Version: 1
Additional Information: Original site: Update once analysis is complete; WARP: Update frequency 1 months
Rights: CC BY-NC 4.0
Fund:
Subject: Seafloor geodesy
Cite as: Japan Coast Guard (2024), GNSS-A observation data in GARPOS format obtained at the SGO-A sites

Title(J): SGO-A観測点で取得されたGARPOSフォーマットのGNSS-A海底地殻変動観測データ
Authors(J): 海上保安庁海洋情報部沿岸調査課海洋防災調査室
Abstract(J): GNSS-A局位置解析ソフトウェアGARPOS（Watanabe et al., 2020, Front. Earth Sci.）での解析用に，音響測距の正味往復走時，船舶のGNSS測位解及び動揺データ，並びに海中音速プロファイルの4つのデータを整理・統合して構成したデータセットです．なお，データの解析・分析手法は研究開発段階のため，改良によってデータを更新することがあります．
Method(J): 音響往復走時は，得られた音響データから冨山（2003, 海洋情報部技報）で提案されたアルゴリズムを用いて算出されたものから海底トランスポンダ固有の応答時間を差し引いたものを用いています． GNSS測位解は，船舶に設置したGNSSアンテナで取得した2 HzのGNSS観測データとIGS最終暦等を用い，RTKLIB（Takasu, 2013）によるキネマティック精密単独測位によって得られたものから固体地球潮汐の影響を除去したものを用いています．動揺データは，50または100 Hzでロール・ピッチ・ヘディングのデータを取得したものを用いています．音響測距信号の送受信時刻でのGNSS測位解と動揺データは，上記データからそれぞれAkima補間及び線形補間により取得しています．海中音速プロファイルは，観測中に投下した複数のXBTやXCTDの水温・塩分プロファイルを平均したうえでDel Grosso (1974) の経験則により音速に変換したものを区分線系関数で表現しています．
Keywords(J): GNSS-A, GNSS-A methodology
Correspondence(J): 海上保安庁海洋情報部沿岸調査課海洋防災調査室
Additional Information(J): Original site: 更新は解析が終了次第なされます; WARP: 更新頻度1か月