Abstract
The volume transport of the Kuroshio, the western boundary current of the North Pacific subtropical gyre, varies vigorously due to merging of disturbances propagating from the entire North Pacific. Taking into account the recirculation in the Shikoku Basin by the zonal observation line at 30°N to the west of the Izu–Ogasawara Ridge, we estimated the volume transport in the top 1,000 m layer toward the Kuroshio Extension region. The volume transport of the local recirculation gyre in the Shikoku Basin increases associated with the westward extension of the gyre, particularly in the period of the large meandering path of the Kuroshio south of Japan. Meanwhile, most of the transport variations toward the Kuroshio Extension region correspond to those of the Kuroshio transport on the continental slope south of Japan, which vary independently of those of the recirculation gyre.
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References
Akitomo K, Ooi TAM, Kutsuwada K (1996) Interannual variability of the Kuroshio transport in response to the wind stress field over the North Pacific: its relation to the path variation south of Japan. J Geophys Res 101:14057–14071
Andres M, Kwon Y-O, Yang J (2011) Observations of the Kuroshio’s barotropic and baroclinic responses to basin-wide wind forcing. J Geophys Res 116. doi:10.1029/2010JC006863
AVISO (2008) SSALTO/DUACS user handbook: (M)SLA and (M)ADT near-real time and delayed time products. Tech. rep., CLS, Ramonville St Agnes
Book JW, Wimbush M, Imawaki S, Ichikawa H, Uchida H, Kinoshita H (2002) Kuroshio temporal and spatial variations south of Japan determined from inverted echo sounder measurements. J Geophys Res 107. doi:10.1029/2001JC000795
Bryden H, Imawaki S (2001) Ocean heat transport. In: Siedler H, Church J, Gould J (eds) Ocean circulation and climate: observing and modeling the global ocean. Academic, New York, pp 455–474
Bryden H, Roemmich D, Church J (1991) Ocean heat transport across 24°N in the Pacific. Deep Sea Res 38:297–324
Dijkstra H (2000) Nonlinear physical oceanography: a dynamical system approach to the large scale ocean circulation and El Niño. Atmospheric and oceanographic sciences library, vol 22. Kluwer, Dordrecht
Hasunuma K, Yoshida K (1978) Splitting of the subtropical gyre in the western North Pacific. J Oceanogr Soc Jpn 34:160–172
Hsiung J (1986) Mean surface energy fluxes over the global ocean. J Geophys Res 91:10585–10606. doi:10.1029/JC091iC09p10585
Ichikawa H, Nakamura H, Nishina A, Higashi M (2004) Variability of northeastward current southeast of northern Ryukyu Islands. J Oceanogr 60:351–363
Ichikawa K (2001) Variation of the Kuroshio in the Tokara Strait induced by meso-scale eddies. J Oceanogr 57:55–68
Imawaki S, Uchida H, Ichikawa H, Fukasawa M, Umatani S, ASUKA Group (2001) Satellite altimeter monitoring the Kuroshio transport south of Japan. Geophys Res Lett 28:17–20
Jayne SR, Hogg NG, Waterman SN, Rainville L, Donohue KA, Watts DR, Tracy KL, MacClean JL, Maltrud ME, Qiu B, Chen S, Hacker P (2009) The Kuroshio Extension and its recirculation gyres. Deep Sea Res I 56:2088–2099. doi:10.1016/j.dsr.2009.08.006
Kakinoki K, Imawaki S, Uchida H, Nakamura H, Ichikawa K, Umatani S, Nishina A, Ichikawa H, Wimbush M (2008) Variations of Kuroshio geostrophic transport south of Japan estimated from long-term IES observations. J Oceanogr 66:373–384
Kashima M, Ito S, Ichikawa K, Imawaki S, Umatani S, Uchida H, Setou T (2009) Quasiperiodic small meanders of the Kuroshio off Cape Ashizuri and their inter-annual modulation caused by quasiperiodic arrivals of mesoscale eddies. J Oceanogr 65:73–80
Kawabe M (1988) Variability of Kuroshio velocity assessed from the sea-level difference between Naze and Nishinoomote. J Oceanogr Soc Jpn 44:293–304
Kawabe M (1995) Variations of current path, velocity, and volume transport of the Kuroshio in relation with the large meander. J Phys Oceanogr 25:3103–3117
Kawabe M (2001) Interannual variations of sea level at Nansei Islands and volume transport of the Kuroshio due to wind changes. J Oceanogr 57:189–205
Konda M, Ichikawa H, Tomita H, Cronin MF (2010) Surface heat flux variations across the Kuroshio Extension as observed by surface flux buoys. J Clim 23:5206–5221. doi:10.1175/2010JCLI3391.1
Munk WH (1950) On the wind-driven ocean circulation. J Meteorol 7:79–93
Nagano A, Ichikawa H, Miura T, Ichikawa K, Konda M, Yoshikawa Y, Obama K, Murakami K (2007) Current system east of the Ryukyu Islands. J Geophys Res 112. doi:10.1029/2006JC003917
Nagano A, Ichikawa K, Ichikawa H, Konda M, Murakami K, (2009) Synoptic flow structures in the confluence region of the Kuroshio and the Ryukyu Current. J Geophys Res 114. doi:10.1029/2008JC005213
Nagano A, Ichikawa K, Ichikawa H, Tomita H, Tokinaga H, Konda M (2010) Stable volume and heat transports of the North Pacific subtropical gyre revealed by identifying the Kuroshio in synoptic hydrography south of Japan. J Geophys Res 115. doi:10.1029/2009JC005747
Nagano A, Ichikawa K, Ichikawa H, Yoshikawa Y, Konda M, Murakami K (2013) Subsurface current structures east of the Amami-Oshima Island based on LADCP observation. J Adv Mar Sci Technol Soc 18 (in press)
Nagano A, Kawabe M (2002) Volume transport and path variation of the Kuroshio. Kaiyo Mont (Special Issue) 31:14–21 (in Japanese)
Nitani H (1972) Beginning of the Kuroshio. In: Stommel H, Yoshida K (eds) Kuroshio—its physical aspects. University of Tokyo Press, Tokyo, pp 129–163
Pedlosky J (1996) Ocean circulation theory. Springer, New York
Stommel H (1948) The westward intensification of wind-driven ocean currents. Trans Am Geophys Union 29:202–206
Sugimoto S, Hanawa K, Narikiyo K, Fujimori M, Suga T (2010) Temporal variations of the net Kuroshio transport and its relation to atmospheric variations. J Oceanogr 66:611–619
Thompson R (1983) Low-pass filters to suppress inertial and tidal frequencies. J Phys Oceanogr 13:1077–1083
Venonis G (1966) Wind-driven ocean circulation—part 2. Numerical solutions of the non-linear problem. Deep Sea Res 13:30–55
Acknowledgments
The authors thank the members on board the R/V “Kaiyo” (cruise numbers KY04-12 and KY05-09) and “Tansei-maru” (KT04-13 and KT05-23) of JAMSTEC for collecting IES and hydrographic data. Also, the authors extend our sincere thanks to the members on board the R/V “Chofu-maru” and “Keifu-maru” of JMA and vessels of JMSDF for their efforts to collect the hydrographic data. Most of this study was done when K. Ichikawa belonged to JAMSTEC. The authors acknowledge Associate Prof. S. Fujio providing the corrected tidal records at Tosa-Shimizu. Thanks are extended to Editor-in-Chief (Prof. T. Hibiya) and anonymous reviewers for their helpful comments. This work was partly supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Grant-in-Aid for Scientific Research on Innovative Areas (22106007).
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Nagano, A., Ichikawa, K., Ichikawa, H. et al. Volume transports proceeding to the Kuroshio Extension region and recirculating in the Shikoku Basin. J Oceanogr 69, 285–293 (2013). https://doi.org/10.1007/s10872-013-0173-9
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DOI: https://doi.org/10.1007/s10872-013-0173-9