Abstract
Seasonal variations of the surface currents in the Tsushima Strait were investigated by analyzing the monthly mean surface currents measured with HF radar. Several new features of the surface currents have been found. One notable feature is the large, complicated seasonal variation in the current structure in the eastern channel of the strait. For example, in the southeastern and northwestern regions of the channel, southwestward countercurrents are found in summer while southeastward acrossshore currents are found in autumn and winter. The wind-driven flow (Ekman flow) as well as surface geostrophic currents are responsible for these complicated variations of the surface currents. To quantify each variation of the flow and current, the wind-driven flow was calculated from the monthly wind (more precisely, the friction velocity) using the monthly speed factor and deflection angle estimated in our previous study, and the surface geostrophic currents were then estimated by subtracting the wind-driven flow from the measured surface currents. It was found that the acrossshore currents are the wind-driven flow, and that the surface geostrophic currents flow almost in the along-shore direction, indicating the validity of the decomposition of the surface velocity into the wind-driven flow and the geostrophic currents using the speed factor and deflection angle. A real-vector empirical orthogonal function (EOF) analysis of the surface geostrophic currents shows a pair of eddies in the lee of Tsushima and Iki Islands as the first mode, which indicates that the southwestward countercurrents in the eastern channel are formed primarily by the incoming Tsushima Warm Current.
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References
Egawa, T., Y. Nagata and S. Sato (1993): Seasonal variation of the current in the Tsushima Strait deduced from ADCP data of ship-of-opportunity. J. Oceanogr., 49, 39–50.
Isobe, A., S. Tawara, A. Kaneko and M. Kawano (1994): Seasonal variability in the Tsushima Warm Current, Tsushima-Korea Strait. Cont. Shelf Res., 14, 23–35.
Isobe, A., M. Ando, T. Watababe, T. Senjyu, S. Sugihara and A. Manda (2002): Freshwater and temperature transports through the Tsushima-Korea Straits. J. Geophys. Res. Oceans, 107, 3065, doi:10.1029/2000JC000702.
Kaihatu, J. M., R. A. Hander, G. O. Marmorino and L. Shay (1998): Empirical orthogonal function analysis of ocean surface currents using complex and real-vector methods. J. Atmos. Oceanic Technol., 15, 927–941.
Kaneko, A., S. K. Byun, S. D. Chang and M. Takahashi (1991): An observation of sectional velocity structures and transport of the Tsushima Current across the Korea Strait. p. 179–195. In Oceanography of Asian Marginal Seas, ed. by K. Takano, Elsevier Sci.
Katoh, O. (1993): Detailed current structures in the eastern channel of the Tsushima Strait in summer. J. Oceanogr., 49, 17–30.
Miita, T. and Y. Ogawa (1984): Tsushima Currents measured with current meters and drifters. p. 67–76. In Ocean Hydrodynamics of the Japan and East China Seas, ed. by T. Ichiye, Elsevier Sci.
Mizuno, S., K. Kawatate and T. Nagahama (1989): Measurements of east Tsushima Current in winter and estimation of its seasonal variability. J. Oceanogr. Soc. Japan, 45, 375–384.
Odamaki, M. (1989): Tides and tidal currents in the Tsushima Strait. J. Oceanogr. Soc. Japan, 45, 65–82.
Senjyu, T., S. Matsui and I. S. Han (2008): Hydrographic conditions in the Tsushima Strait revisited. J. Oceanogr., 64, 171–183.
Takikawa, T., J. H. Yoon and K. D. Cho (2003): Tidal currents in the Tsushima Straits estimated from ADCP data by ferryboat. J. Oceanogr., 59, 37–47.
Takikawa, T., J. H. Yoon and K. D. Cho (2005): The Tsushima Warm Current through Tsushima Straits estimated from ferryboat ADCP data. J. Phys. Oceanogr., 35, 1154–1168.
Teague, W. J., H. T. Perkins, G. A. Jacobs and J. W. Book (2001): Tide observations in the Korea-Tsushima Strait. Cont. Shelf Res., 21, 545–561.
Teague, W. J., P. A. Hwang, G. A. Jacobs, J. W. Book and H. T. Perkins (2005): Transport variability across Korea/Tsushima Strait and the Tsushima Island wake. Deep-Sea Res. II, 52, 1784–1801.
Yelland, M. and P. K. Taylor (1996): Wind stress measurement from the open ocean. J. Phys. Oceanogr., 26, 541–558.
Yoshikawa, Y. and A. Masuda (2009): Seasonal variations in the speed factor and deflection angle of the wind-driven surface flow in the Tsushima Strait. J. Geophys. Res. Oceans, 114, C12022, doi:10.1029/2009JC005632.
Yoshikawa, Y., A. Masuda, K. Marubayashi, M. Ishibashi and A. Okuno (2006): On the accuracy of HF radar measurement in the Tsushima Strait. J. Geophys. Res. Oceans, 111, C04009, doi:10.1029/2005JC003232.
Yoshikawa, Y., T. Matsuno, K. Marubayashi and K. Fukudome (2007): A surface velocity spiral observed with ADCP and HF radar in the Tsushima Strait. J. Geophys. Res. Oceans, 112, C06022, doi:10.1029/2006JC003625.
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Yoshikawa, Y., Masuda, A., Marubayashi, K. et al. Seasonal variations of the surface currents in the Tsushima Strait. J Oceanogr 66, 223–232 (2010). https://doi.org/10.1007/s10872-010-0020-1
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DOI: https://doi.org/10.1007/s10872-010-0020-1