Ocean Dynamics

, Volume 66, Issue 1, pp 77–97 | Cite as

Development of an operational coastal model of the Seto Inland Sea, Japan

  • Kei SakamotoEmail author
  • Goro Yamanaka
  • Hiroyuki Tsujino
  • Hideyuki Nakano
  • Shogo Urakawa
  • Norihisa Usui
  • Mikitoshi Hirabara
  • Koji Ogawa
Part of the following topical collections:
  1. Topical Collection on Coastal Ocean Forecasting Science supported by the GODAE OceanView Coastal Oceans and Shelf Seas Task Team (COSS-TT)


We have developed a coastal model of the Seto Inland Sea, Japan, for a monitoring and forecasting system operated by the Japan Meteorological Agency (JMA). We executed a hindcast experiment using reanalysis datasets for the atmospheric and lateral boundaries without ocean initialization by data assimilation. The seasonal variability is verified to be realistic by comparing sea surface temperature and salinity of the hindcast experiment with observations. With a horizontal resolution of approximately 2 km, the model represents explicitly various coastal phenomena with a scale of 10–100 km, such as the Kuroshio water intrusion into Japanese coasts. This leads to good representation of intramonthly variations. For example, intensity of the sea level undulations with a period shorter than 23 days shows 1.6-fold improvement, as compared to the present model of JMA with the horizontal resolution of approximately 10 km. In addition to the increased resolution, the model is optimized for coastal modeling as follows. Incorporation of a tidal mixing parameterization reduces a high temperature bias in the Bungo Channel (a western channel of the Seto Inland Sea) and contributes to formation of a frontal structure. An accurate dataset of the river discharges is used for runoff, which has a strong impact on salinity. Enhancement of coastal friction improves surface currents. Owing to the increased resolution and these optimizations, the model shows realistic variability in a wide temporal range from several days to seasons. Root-mean-square errors of sea surface temperature and heights are evaluated as 1–2 K and 7–10 cm, respectively, without data assimilation. In the eastern part, however, the predictability is relatively low, which might be related to representation of an eastward mean flow in the Seto Inland Sea.


Coastal modeling Seto Inland Sea Operational model 



We thank the members of the oceanography and geochemistry research department of Meteorological Research Institute for fruitful discussions and helpful comments. This work was funded by MRI and was partly supported by JSPS KAKENHI Grant Number 24740323.


  1. Adcroft A, Campin JM (2004) Rescaled height coordinates for accurate representation of free-surface flows in ocean circulation models. Ocean Modell 7:269–284. doi: 10.1016/j.ocemod.2003.09.003 CrossRefGoogle Scholar
  2. Arakawa A (1972) Design of the ucla general circulation model. numerical simulation of weather and climate. Tech Rep. 7. Dept of Meteorology, University of California, Los AngelesGoogle Scholar
  3. Chang P H, Guo X, Takeoka H (2009) A numerical study on the seasonal circulation in the Seto Inland Sea, Japan. J Oceanogr 65(6):721–736CrossRefGoogle Scholar
  4. Fujiwara T (1983) Water mass exchange between the Seto Inland Sea and the open ocean. Umi to Sora 59 (1):7–17. (in Japanese)Google Scholar
  5. Futamura A, Takeoka H, Guo X (2005) Current, water exchange and heat budget in the stratified region of Hiuchi-Nada. Oceanography in Japan 14(3):429–440CrossRefGoogle Scholar
  6. Griffies SM, Hallberg RW (2000) Biharmonic friction with a Smagorinsky-like viscosity for use in large-scale eddy-permitting ocean models. Mon Wea Rev 128:2935–2946. doi: 10.1175/1520-0493(2000)128<2935:BFWASL>2.0.CO;2 CrossRefGoogle Scholar
  7. Hanawa K, Mitsudera H (1985) On the data processings of daily mean values of oceanographical data: Note on the daily mean sea-level data. Bulletin on Coastal Oceanography 23(1):79–87. (in Japanese)Google Scholar
  8. Imasato N, Qiu B (1987) An event in water exchange between continental shelf and the Kuroshio off southern Japan: Lagrangian tracking of a low-salinity water mass on the Kuroshio. J Phys Oceanogr 17:953–968. doi: 10.1175/1520-0485(1987)017<0953:AEIWEB>2.0.CO;2 CrossRefGoogle Scholar
  9. Ishizaki H, Yamanaka G (2010) Impact of explicit sun altitude in solar radiation on an ocean model simulation. Ocean Modell 33:52–69. doi: 10.1016/j.ocemod.2009.12.002 CrossRefGoogle Scholar
  10. Ishizaki S, Soga T, Usui N, Fujii Y, Tsujino H, Ishikawa I, Yoshioka N, Kuragano R, Kamachi M (2009) Overview and operational system development of MOVE/MRI.COM. Weather Service Bulletin 76:S1—S15. (in Japanese)Google Scholar
  11. Isobe A, Guo X, Takeoka H (2010) Hindcast and predictability of sporadic Kuroshio-water intrusion (Kyucho in the Bungo Channel) into the shelf and coastal waters. J Geophys Res 115:C04,023. doi: 10.1029/2009JC005818 Google Scholar
  12. Isobe A, Kako S, Guo X, Takeoka H (2012) Ensemble numerical forecasts of the sporadic Kuroshio water intrusion (kyucho) into shelf and coastal waters. Ocean Dyn 62(4):633–644CrossRefGoogle Scholar
  13. Kunii M, Fujiwara T (2006) Through flow of the Seto Inland Sea driven by the sea level difference between western and eastern boundaries. Umi to Sora 81(2):63–72. (in Japanese)Google Scholar
  14. Kuroda H, Setou T, Aoki K, Takahashi D, Shimizu M, Watanabe T (2013) A numerical study of the Kuroshio-induced circulation in Tosa Bay, off the southern coast of Japan. Continental Shelf Res 53:50–62. doi: 10.1016/j.csr.2012.12.005 CrossRefGoogle Scholar
  15. Kuroda H, Hirota Y, Setou T, Aoki K, Takahashi D, Watanabe T (2014) Properties of winter mixed layer variability on the shelf-slope region facing the Kuroshio - study of Tosa Bay, southern Japan. Ocean Dyn 64(1):47–60. doi: 10.1007/s10236-013-0670-9 CrossRefGoogle Scholar
  16. Large WG, Yeager SG (2004) Diurnal to decadal global forcing for coean and sea-ice models: the data sets and flux climatologies. NCAR Tech. Note: TN-460+STR, CGD Division of the Natinal Center for Atmospheric ResearchGoogle Scholar
  17. Lee HC, Rosati A, Spelman MJ (2006) Barotropic tidal mixing effects in a coupled climate model: Oceanic conditions in the Northern Atlantic. Ocean Modell 11(3):464–477. doi: 10.1016/j.ocemod.2005.03.003 Google Scholar
  18. Miyazawa Y, Miyama T, Varlamov S M, Guo X, Waseda T (2012) Open and coastal seas interactions south of Japan represented by an ensemble Kalman filter. Ocean Dyn 62(4):645–659CrossRefGoogle Scholar
  19. Nagai T, Hibiya T (2012) Numerical simulation of tidally induced eddies in the Bungo Channel: a possible role for sporadic Kuroshio-wate intrusion (kyucho). J Oceanogr 68:797–806. doi: 10.1007/s10872-012-0141-9 CrossRefGoogle Scholar
  20. Nakada S, Ishikawa Y, Awaji T, In T, Shima S, Nakayama T, Isada T, Saitoh SI (2012) Modeling runoff into a region of freshwater influence for improved ocean prediction: Application to Funka Bay. Hydrological Research Letters 6:47–52. doi: 10.3178/HRL.6.47 CrossRefGoogle Scholar
  21. Nishiyama K (ed.) (2013) Climate and marine conditions of the Seto Inland Sea. The Marine Meteorological Society. (in Japanese)Google Scholar
  22. Noh Y, Kim H J (1999) Simulations of temperature and turbulence structure of the oceanic boundary layer with the improved near-surface process. J Geophys Res 104:15CrossRefGoogle Scholar
  23. Prather MJ (1986) Numerical advection by conservation of second-order moments. J Geophys Res 91 (D6):6671–6681. doi: 10.1029/JD091iD06p06671 CrossRefGoogle Scholar
  24. Sakamoto K, Tsujino H, Nishikawa S, Nakano H, Motoi T (2010) Dynamics of the Coastal Oyashio and its seasonal variation in a high-resolution western North Pacific Ocean model. J Phys Oceanogr 40(6):1283–1301. doi: 10.1175/2010JPO4307.1 CrossRefGoogle Scholar
  25. Sakamoto K, Tsujino H, Nakano H, Hirabara M, Yamanaka G (2013a) A practical scheme to introduce explicit tidal forcing into an OGCM. Ocean Sci 9:1089–1108. doi: 10.5194/os-9-1089-2013 CrossRefGoogle Scholar
  26. Sakamoto K, Yamanaka G, Tsujino H, Nakano H, Hirabara M (2013b) Development of a 2km-resolution Japanese coastal ocean model: Toward a next-generation operational monitoring and forecasting system. Weather Service Bulletin 80:S99—S109. (in Japanese)Google Scholar
  27. Sakamoto K, Yamanaka G, Tsujino H, Nakano H, Hirabara M (2014) Development of a 2km-resolution Seto Inland Sea model, MRI.COM-Seto, and a Japanese coastal ocean model, MRI.COM-JPN. Weather Service Bulletin 81:S63—S75. (in Japanese)Google Scholar
  28. Sun YJ, Isobe A (2008) Lagrangian H/U3 values computed around fronts using a fine-resolution numerical model and ferryboat-monitored SST dataset. J Phys Oceanogr 38(11):2575–2586. doi: 10.1175/2008JPO3839.1 CrossRefGoogle Scholar
  29. Toda T (1992) Double structure of the coastal front in the Kii Channel, Japan, during winter. J Geophys Res 97(C7):11, 333–11, 342. doi: 10.1029/92JC00589 CrossRefGoogle Scholar
  30. Toda T (1993) Movement of the surface front by Kuroshio frontal eddy. J Geophys Res 98(C9):16,331–16,339,. doi: 10.1029/93JC01027 CrossRefGoogle Scholar
  31. Tsujino H, Motoi T, Ishikawa I, Hirabara M, Nakano H, Yamanaka G, Yasuda T, Ishizaki H (2010) Reference manual for the Meteorological Research Institute Community Ocean Model (MRI.COM) version 3. Tech Rep. 59. Meteorological Research Institute, JapanGoogle Scholar
  32. Tsujino H, Hirabara M, Nakano H, Yasuda T, Motoi T, Yamanaka G (2011) Simulating present climate of the global ocean-ice system using the Meteorological Research Institute Community Ocean Model (MRI.COM): simulation characteristics and variability in the Pacific sector. J Oceanogr 67:449–479. doi: 10.1007/s10872-011-0050-3 CrossRefGoogle Scholar
  33. Tsujino H, Sakamoto K, Usui N (2015) Development of coastal ocean models at the Meteorological Research Institute of the Japan Meteorological Agency. Bulletin of Coastal Oceanography 5(2):119–129. (in Japanese)Google Scholar
  34. Tsutsumi E, Guo X, Yoshie N, Matsuno T, Mano T, Nakagawa M (2014) Vertical mixing in Iyo-Nada: Comparison between a stratification period and a non-stratification period.. In: Proceedings of the Oceanographic Society of Japan fall meeting, p 64. (in Japanese)Google Scholar
  35. Uchiyama Y, Kuriyama T, Miyazawa Y (2012) Impact of the Kuroshio paths on oceanic and estuarine circulations in and around Seto Inland Sea. Journal of Japan Society of Civil Engineers, Ser B2 (Coastal Engineering) 68 (2):I441–I445. doi: 10.2208/kaigan.68.I_441 Google Scholar
  36. Urakawa L S, Kurogi M, Yoshimura K, Hasumi H (2015) Modeling low salinity waters along the coast around japan using a high resolution river discharge data set. J Oceanogr pp –. (submitted)Google Scholar
  37. Usui N, Sakamoto K, Ogawa K, Fujii Y, Tsujino H, Yamanaka G, Kuragano T, Kamachi M (2014) Hindcast experiment of an abnormal tidal height event in the Seto Inland Sea by a monitoring and forecasting system of Japanese coastal seas. Weather Service Bulletin 81:S53—S62. (in Japanese)Google Scholar
  38. Usui N, Fujii Y (2015) Sakamoto K. Development of a four-dimensional variational assimilation system toward coastal data assimilation around Japan. Monthly Weather Review pp –, Kamachi M. (submitted)Google Scholar
  39. Yanagi T, Koike T (1987) Seasonal variation in thermohaline and tidal fronts, Seto Inland Sea, Japan. Continental Shelf Res 7(2):149–160. doi: 10.1016/0278-4343(87)90076-8 CrossRefGoogle Scholar
  40. Yanagi T, Ohba T (1985) A tidal front in the Bungo Channel. Bulletin on Coastal Oceanography 23 (1):19–25. (in Japanese)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Kei Sakamoto
    • 1
    Email author
  • Goro Yamanaka
    • 1
  • Hiroyuki Tsujino
    • 1
  • Hideyuki Nakano
    • 1
  • Shogo Urakawa
    • 1
  • Norihisa Usui
    • 1
  • Mikitoshi Hirabara
    • 2
  • Koji Ogawa
    • 3
  1. 1.Meteorological Research InstituteTsukubaJapan
  2. 2.Global Environment and Marine DepartmentJapan Meteorological AgencyTokyoJapan
  3. 3.Fukuoka Regional HeadquartersJapan Meteorological AgencyFukuokaJapan

Personalised recommendations