Improvement of Submerged Doppler-Type Directional Wave Meter and Its Application to Field Observations

Hashimoto, Noriaki; Mitsui, Masao; Goda, Yoshimi; Nagai, Toshihiko; Takahashi, Tomoharu

doi:10.1061/9780784402429.050

Cited by 9 publications

(2 citation statements)

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“…Fig.9 shows the observed low-pass-filtered low frequency sea level fluctuation data ( [13] near Kamaishi area with 3 sensors: (1) new offshore GPS Buoy 204m deep, (2) existing NOWPHAS near-shore seabed acoustic wave gauge at 50m deep, and (3) coastal tide station of the Japanese Coastal Guard. 10. Because the tsunami heights were not so large compared to then existing normal sea's low frequency fluctuation level, the first tsunami wave arrival was not clear for any data at these 3 stations.…”

Section: Gps Buoy Systemmentioning

confidence: 95%

Characteristics of the Observed Offshore Wave Data by the GPS Buoys

Nagai

Shimizu

Sasaki

et al. 2008

OCEANS 2008 - MTS/IEEE Kobe Techno-Ocean

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This paper explained characteristics of the observed offshore wave, tsunami and tide data for the half year in 2007, obtained by the two sets of the GPS buoy system installed off the Northern Pacific Coast of Japan by the Ports and Airports Department of the Tohoku Regional Development Bureau of the Ministry of Land, Infrastructure and Transport Japan. Two sets of the GPS buoy successfully observed, wave climate, abnormal high waves, and offshore astronomical tides with little data luck only about 2% of the total observation data. Offshore GPS buoys observed much bigger significant wave heights in both normal and abnormal sea states than the shallower seabed wave gauges, meaning that deep-sea wave observation is necessary in order to obtain offshore wave conditions.

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Section: Gps Buoy Systemmentioning

confidence: 95%

Characteristics of the Observed Offshore Wave Data by the GPS Buoys

Nagai

Shimizu

Sasaki

et al. 2008

OCEANS 2008 - MTS/IEEE Kobe Techno-Ocean

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“…Bubble gauges were used to estimate water column height based on hydrostatic pressure equilibrium (Pugh 1972;Woodworth and Smith 2003). Travel time of ultrasonic wave reflection is used to measure the distance between sea bottom and sea surface (Takayama et al 1994;Hashimoto et al 1996). Pressure gauges at the deep-sea bottom feel the total water column height above the seafloor (Filloux 1983;Eble and Gonzalez 1991;Hino et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Extracting clearer tsunami currents from shipborne Automatic Identification System data using ship yaw and equation of ship response

Inazu

Ikeya

Iseki

et al. 2020

Earth Planets Space

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We have explored tsunami current signals in maritime Automatic Identification System (AIS) data during the 2011 Tohoku, Japan, tsunami. The AIS data were investigated in detail taking into account ship motion and response to tsunami current. Ship velocity derived from AIS data was divided into two components in terms of the ship heading: heading-normal and heading-parallel directions. The heading-normal velocity showed good agreement with the simulated tsunami current, as mentioned in our former research. Here, we found the heading-normal velocity was contaminated by non-tsunami noises that were mostly related to the ship yaw motion around the pivot point. The noises due to the yaw motion were reasonably corrected in the heading-normal velocity. The corrected headingnormal velocity clearly showed better agreement with the simulated tsunami current. Although the heading-parallel velocity is basically the navigation speed, and is mostly controlled by ships' captain, we could find the heading-parallel velocity was also drifted by tsunami currents. The corrected heading-normal velocity was still a ship response to the tsunami current. Based on an equation of a ship response to tsunami currents, we numerically estimated tsunami current from the corrected heading-normal velocity. We could find very slight improvements in estimating the tsunami currents, which indicated that this operation possibly worked as a secondary correction. Tsunami currents of tens of centimeters per second are expected to be suitably detected using AIS based on discussion on detection limit.

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Wave height measurements using acoustic surface tracking

Pedersen

Nylund

Dolle³

Oceans '02 MTS/IEEE

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Improvement of Submerged Doppler-Type Directional Wave Meter and Its Application to Field Observations

Cited by 9 publications

References 0 publications

Characteristics of the Observed Offshore Wave Data by the GPS Buoys

Characteristics of the Observed Offshore Wave Data by the GPS Buoys

Extracting clearer tsunami currents from shipborne Automatic Identification System data using ship yaw and equation of ship response

Wave height measurements using acoustic surface tracking

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