Abstract
Subinertial and seasonal variations in the Soya Warm Current (SWC) are investigated using data obtained by high frequency (HF) ocean radars, coastal tide gauges, and a bottom-mounted acoustic Doppler current profiler (ADCP). The HF radars clearly captured the seasonal variations in the surface current fields of the SWC. Almost the same seasonal cycle was repeated in the period from August 2003 to March 2007, although interannual variations were also discernible. In addition to the annual and interannual variations, the SWC exhibited subinertial variations with a period of 5–20 days. The surface transport by the SWC was significantly correlated with the sea level difference between the Sea of Japan and Sea of Okhotsk for both the seasonal and subinertial variations, indicating that the SWC is driven by the sea level difference between the two seas. The generation mechanism of the subinertial variation is discussed using wind data from the European Centre for Medium-range Weather Forecasts (ECMWF) analyses. The subinertial variations in the SWC were significantly correlated with the meridional wind stress component over the region. The subinertial variations in the sea level difference and surface current delay from the meridional wind stress variations by one or two days. Sea level difference through the strait caused by wind-generated coastally trapped waves (CTWs) along the east coast of Sakhalin and west coast of Hokkaido is considered to be a possible mechanism causing the subinertial variations in the SWC.
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References
Aota, M. (1975): Studies on the Soya Warm Current. Low Temp. Sci., Ser. A, 33, 151–172 (in Japanese with English abstract).
Aota, M. (1984): Oceanographic structure of the Soya Warm Current. Bull. Coast. Oceanogr., 22, 30–39 (in Japanese).
Aota, M. and T. Kawamura (1978): Observation of oceanographic condition in the Okhotsk Sea coast of Hokkaido in winter. Low Temp. Sci., Ser. A, 37, 93–105 (in Japanese with English abstract).
Aota, M. and M. Matsuyama (1987): Tidal current fluctuations in the Soya Current. J. Oceanogr. Soc. Japan, 43, 276–282.
Barrick, D. E. and B. J. Lipa (1997): Evolution of bearing determination of HF current map** radars. Oceanography, 10, 72–75.
Barrick, D. E., M. W. Evans and B. L. Weber (1977): Ocean surface currents mapped by radar. Science, 198, 138–144.
Ebuchi, N., Y. Fukamachi, K. I. Ohshima, K. Shirasawa, M. Ishikawa, T. Takatsuka, T. Daibo and M. Wakatsuchi (2006): Observation of the Soya Warm Current using HF ocean radar. J. Oceanogr., 62, 47–61.
Emery, W. J. and R. E. Thomson (2001): Data Analysis Methods in Physical Oceanography (Second and Revised Edition). Elsevier, Amsterdam, The Netherlands, 638 pp.
Fukamachi, Y., I. Tanaka, K. I. Ohshima, N. Ebuchi, G. Mizuta, H. Yoshida, S. Takayanagi and M. Wakatsuchi (2008): Volume transport of the Soya Warm Current revealed by bottom-mounted ADCP and ocean-radar measurement. J. Oceanogr., 64, 385–392.
Gill, A. E. (1982): Atmosphere-Ocean Dynamics. Academic Press, San Diego, California, U.S.A., 662 pp.
Gill, A. E. and E. H. Schumann (1974): The generation of long shelf waves by the wind. J. Phys. Oceanogr., 4, 83–90.
Hanawa, K. and H. Mitsudera (1985): On the data processing of daily mean values of oceanographic data.—Note on the daily mean sea-level data—. Bull. Coast. Oceanogr., 23, 79–87 (in Japanese).
Ishikawa, K. (2007): Variations of the Tsushima Warm Current system deduced from sea level differences across straits. Master’s thesis of the Graduate School of Environmental Science, Hokkaido University, 35 pp. (in Japanese).
Ishizu, M., Y. Kitade and M. Matsuyama (2006): Formation mechanism of the cold-water belt formed off the Soya Warm Current. J. Oceanogr., 62, 457–471.
Jacobs, G. A., D. S. Ko, H. Ngodock, R. H. Preller and S. K. Riedlinger (2005): Synoptic forcing of the Korea Strait transport. Deep-Sea Res. II, 52, 1490–1504.
Japan Coast Guard (1992): Tidal Harmonic Constants Tables, Japanese Coast. Hydrographic Publication, No. 742, 762 pp.
Ko, D. S., R. H. Preller, G. A. Jacobs, T. Y. Tang and S. F. Lin (2003): Transport reversals at Taiwan Strait during October and November 1999. J. Geophys. Res., 108(C11), 3370, doi:10.1029/2003JC001836.
Lipa, B. J. and D. E. Barrick (1983): Least-squares method for the extraction of surface currents from CODAR crossed-loop data: Applications at ARSLOE. IEEE J. Ocean. Eng., OE-8, 226–253.
Lyu, S. J. and K. Kim (2005): Subinertial to interannual transport variations in the Korea Strait and their possible mechanisms. J. Geophys. Res., 110, C12016, doi:10.1029/2004JC002651.
Lyu, S. J., K. Kim and H. T. Perkins (2002): Atmospheric pressure-forced subinertial variations in the transport through the Korea Strait. Geophys. Res. Lett., 29(9), 1294, doi:10.1029/2001GL014366.
Matsuyama, M., M. Aota, I. Ogasawara and S. Matsuyama (1999): Seasonal variation of Soya Current. Umi no Kenkyu, 8, 333–338 (in Japanese with English abstract and figure captions).
Matsuyama, M., M. Wadaka, T. Abe, M. Aota and Y. Koike (2006): Current structure and volume transport of the Soya Warm Current in summer. J. Oceanogr., 62, 197–205.
Minobe, S. and M. Nakamura (2004): Interannual to decadal variability in the southern Okhotsk Sea based on a new gridded upper water temperature data set. J. Geophys. Res., 109, C09S05, doi:10.1029/2003JC001916.
Mizuta, G., K. I. Ohshima, Y. Fukamachi and M. Wakatsuchi (2005): The variability of the East Sakhalin Current induced by winds over the continental shelf and slope. J. Mar. Res., 63, 1017–1039.
Ohshima, K. I. (1994): The flow system in the Japan Sea caused by a sea level difference through shallow straits. J. Geophys. Res., 99, 9925–9940.
Ohshima, K. I. and M. Wakatsuchi (1990): A numerical study of barotropic instability associated with the Soya Warm Current in the Sea of Okhotsk. J. Phys. Oceanogr., 20, 570–584.
Onishi, M., Y. Isoda, H. Kuroda, M. Iwahashi, C. Satoh, T. Nakayama, T. Ito, K. Iseda, K. Nishizawa, S. Shima and O. Togawa (2004): Winter transport and tidal current in the Tsugaru Strait. Bull. Fish. Sci. Hokkaido Univ., 55, 105–119.
Park, J.-H. and D. R. Watts (2005): Response of the southwestern Japan/East Sea to atmospheric pressure. Deep-Sea Res., 52, 1671–1683.
Smith, S. D. (1988): Coefficients for sea surface wind stress, heat flux and wind profiles as a function of wind speed and temperature. J. Geophys. Res., 93, 15,467–15,472.
Takeyama, Y. (2002): Variation of the Soya Warm Current in winter. Master’s thesis of the Graduate School of Environmental Earth Science, Hokkaido University, 75 pp. (in Japanese).
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.
Tanaka, I. and A. Nakata (1999): Results of direct current measurement in the La Perouse Strait (the Soya Strait), 1995–1998. PICES Sci. Rep., 12, 173–176.
Thompson, R. O. R. Y. (1983): Low-pass filters to suppress inertial and tidal frequencies. J. Phys. Oceanogr., 13, 1077–1083.
Tsu**o, H., H. Nakano and T. Motoi (2008): Mechanism of currents through the straits of the Japan Sea: mean state and seasonal variation. J. Oceanogr., 64, 141–161.
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Ebuchi, N., Fukamachi, Y., Ohshima, K.I. et al. Subinertial and seasonal variations in the Soya Warm Current revealed by HF ocean radars, coastal tide gauges, and bottom-mounted ADCP. J Oceanogr 65, 31–43 (2009). https://doi.org/10.1007/s10872-009-0003-2
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DOI: https://doi.org/10.1007/s10872-009-0003-2