Swell-dominant surface waves observed by a moored buoy with a GPS wave sensor in Otsuchi Bay, a ria in Sanriku, Japan
Real-time monitoring of wind and surface waves in Otsuchi Bay, Iwate, Tohoku, Japan, commenced in October 2012, using a mooring buoy with an ultrasonic anemometer and a single-mode GPS wave sensor. Wind and wave data are distributed hourly in real time via the Internet along with a chart of their time series. We analyzed data monitored in the first 3 months in order to assess the variability and occurrence of wind and waves and to elucidate the main reasons for wave variation in Otsuchi Bay. The monitoring data revealed that surface waves in the bay were predominantly affected by swells propagated from the northeastern offshore region and that the wave height was significantly correlated with the component of wind velocity toward Otsuchi Bay in the northeastern offshore region that faces the bay mouth. The offshore wind field was expected to provide information useful for predicting coastal waves in a ria bay in Sanriku such as Otsuchi Bay. However, it should be emphasized that the horizontal distribution of the offshore wind field which has a significant effect on the surface waves in a ria bay depends heavily on the topographic shape of the bay.
KeywordsSurface wave Otsuchi Bay GPS wave sensor Swell Ria coast
The authors would like to express their great appreciation to K. Kogure and A. Tsuda for their encouraging promotion of this study. We also are deeply appreciative of the Kamaishi-Tobu Fishermen’s cooperative association (I. Ogawara, President) for providing facilities to moor the buoy in close vicinity to their aquaculture systems for the brown seaweed wakame. Mooring and maintenance of the buoy have been enormously supported by M. Kurosawa, M. Hirano, T. Suzuki, and other staff of the International Coastal Research Center, the Atmosphere and Ocean Research Institute at the University of Tokyo. We are also appreciative of the Shin-Otsuchi Fishermen’s cooperative association and the Iwate Fisheries Technology Center for their helpful advice on operating the buoy. Wave data recorded by the NOWPHAS were downloaded from its website (http://www.mlit.go.jp/kowan/nowphas/), and sea–wind data simulated by the Japanese Meteorological Agency were from the data server of the GFD Dennou Club (http://database.rish.kyoto-u.ac.jp/arch/jmadata/data/gpv/netcdf/). Some of the figures were drawn using information from the GFD Dennou Library. Financial support for this study was provided by the Tohoku Ecosystem-Associated Marine Sciences, subsidized by the Ministry of Education, Culture, Sports, Science and Technology.
- Harigae M, Yamaguchi I, Kasai T, Igawa H, Nakanishi H, Murayama T, Iwanaka Y, Suko H (2004) Abreast of the waves: open-sea sensor to measure height and direction. GPS World 16:16–27Google Scholar
- Hofmann-Wellenhof B, Lichtenegger H, Walse E (2007) GNSS-global navigation satellite systems, GPS, GLONASS, Galileo, and more. Springer, New York, p 548Google Scholar
- Isobe M, Kondo K, Horikawa K (1984a) Extension of MLM for estimating directional wave spectrum. Proc. Symp. on Description and Modeling of Directional Seas A-6, p 15Google Scholar
- Isobe M, Kondo K, Horikawa K (1984b) Extension of MLM for estimating directional wave spectrum. Proc Coast Eng Jpn Soc Civ Eng 31:173–177 (in Japanese) Google Scholar
- Kawaguchi K, Kawai H, Satoh M, Chimoto T, Yamaya S (2011) Correlativity of observed wave data between GPS-mounted buoy and coastal wave gauge on the northern Pacific side in Tohoku district. J Jpn Soc Civ Eng Ser B2 67(2):I_436–I_440 (in Japanese with English abstract) Google Scholar
- Kawai H, Satoh M, Kawaguchi K, Seki K (2012) Offshore wave characteristics observed by GPS buoys on the Tohoku to Shikoku district coast of the Pacific ocean, Japan. Tech Note Port Airpt Res Inst 1249:1–51 (in Japanese with English abstract) Google Scholar
- Kawamata S (2001) Effect of waves on grazing by sea urchins and abalone on the coast of northern Japan. Bull Fish Res Agency 1:59–107 (Doctor thesis in Japanese with English abstract and captions) Google Scholar
- Mei CC (1989) The applied dynamics of ocean surface waves, 2nd edn. World Scientific, Singapore, p 760Google Scholar
- Otobe H, Onishi H, Inada M, Michida Y, Terazaki M (2009) Estimation of water circulation in Otsuchi Bay, Japan inferred from ADCP observation. Coast Mar Sci 33(1):78–86Google Scholar
- Sugimoto S, Chikasawa M (2008) A study on Japanese coastal wave characteristics using coastal wave observation by Japan Meteorological Agency. Weather Serv Bull 75:S77–S95 (in Japanese) Google Scholar
- Tolman HL (2002) User manual and system documentation of WAVEWATCH-III version 2.22. NOAA/NWS/NCEP/OMB technical note, 222, p 133Google Scholar