Abstract
Temperature and salinity data from 2003 through 2006 from Argo profiling floats have been analyzed to examine the formation and circulation of the North Pacific Subtropical Mode Water (STMW) and the interannual variation of its properties over the entire distribution region. STMW is formed in late winter in the zonally-elongated recirculation gyre south of the Kuroshio and its extension, which extends north of ∼28°N, from 135°E to near the date line. The recirculation gyre consists of several anticyclonic circulations, in each of which thick STMW with a characteristic temperature is formed. After spring, the thick STMW tends to be continually trapped in the respective circulations, remaining in the formation region. From this stagnant pool of thick STMW, some portion seeps little by little into the southern region, where southwestward subsurface currents advect relatively thin STMW as far as 20°N to the south and just east of Taiwan to the west. The STMW formed in the recirculation gyre becomes colder, less saline, and denser to the east, with an abrupt change of properties across 140°E and a gradual change east of 140°E. The STMW formed east of 140°E exhibits coherent interannual variations, increasing its temperature by ∼1°C from 2003 through 2006 and also increasing its salinity by ∼0.05 from 2003 through 2005. These property changes are clearly detected in the southern region as far downstream as just east of Taiwan, with reasonable time lags.
Similar content being viewed by others
References
Akima, H. (1970): A new method of interpolation and smooth curve fitting based on local procedures. J. Assoc. Comput. Math., 17, 589–602.
Argo Science Team (2001): Argo: The global array of profiling floats. p. 248–258. In Observing the Oceans in the 21st Century, ed. by C. J. Koblinsky and N. R. Smith, GODAE Project Office, Bureau of Meteorology, Melbourne.
Bingham, F. M. (1992): Formation and spreading of Subtropical Mode Water in the North Pacific. J. Geophys. Res., 97, 11177–11189.
Bretherton, F. P., R. E. Davis and C. B. Fandry (1976): A technique for objective analysis and design of oceanographic experiment applied to MODE-73. Deep-Sea Res., 23, 559–582.
Cannon, G. A. (1966): Tropical waters in the western Pacific Oceans, August–September 1957. Deep-Sea Res., 13, 1139–1148.
Conkright, M. E., R. A. Locarnini, H. E. Garcia, T. D. O’Brien, T. P. Boyer, C. Stephens and J. I. Antonov (2002): World Ocean Atlas 2001: Objective Analysis, Data Statistics, and Figures, CD-ROM Documentation. National Oceanographic Data Center, Silver Spring, MD, 17 pp.
Ducet, N., P. Y. Le Traon and G. Reverdin (2000): Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and-2. J. Geophys. Res., 105, 19477–19498.
Ebuchi, N. and K. Hanawa (2001): Trajectory of mesoscale eddies in the Kuroshio recirculation region. J. Oceanogr., 57, 471–480.
Hanawa, K. (1987): Interannual variations of the winter-time outcrop area of Subtropical Mode Water in the western North Pacific Ocean. Atmos. Ocean, 25, 358–374.
Hanawa, K. and J. Kamada (2001): Variability of core layer temperature (CLT) of the North Pacific Subtropical Mode Water. Geophys. Res. Lett., 28, 2229–2232.
Hanawa, K. and L. D. Talley (2001): Mode waters. p. 373–386. In Ocean Circulation and Climate, ed. by J. Church et al., Academic Press, London.
Hanawa, K. and H. Yoritaka (2001): North Pacific Subtropical Mode Waters observed in long XBT cross sections along 32.5°N line. J. Oceanogr., 57, 679–692.
Hayashi, K., T. Soga, Y. Takatsuki and K. Ishikawa (2005): Salinity increasing trend of the North Pacific Tropical Water in recent years. p. 278. In Abstracts of 2005 Spring Meeting of Oceanogr. Soc. Japan, Tokyo Univ. Mar. Sci. Tech., Tokyo (in Japanese).
Japan Meteorological Agency (2005): Data Report of Oceanographic and Marine Meteorological Observations. No. 94.
Japan Meteorological Agency (2006): Data Report of Oceanographic and Marine Meteorological Observations. No. 95.
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.
Kawai, H. (1972): Hydrography of the Kuroshio Extension. p. 235–352. In Kuroshio—Its Physical Aspects, ed. by H. Stommel and K. Yoshida, Univ. Tokyo Press, Tokyo.
Kistler, R., E. Kalnay, W. Collins, S. Saha, G. White, J. Woollen, M. Chelliah, W. Ebisuzaki, M. Kanamitsu, V. Kousky, H. van den Dool, R. Jenne and M. Fiorino (2001): The NCEP-NCAR 50-Year Reanalysis: Monthly Means CD-ROM and Documentation. Bull. Amer. Meteor. Soc., 82, 247–268.
Kubokawa, A. (1999): Ventilated thermocline strongly affected by a deep mixed layer: A theory for subtropical countercurrent. J. Phys. Oceanogr., 29, 1314–1333.
Kubokawa, A. and T. Inui (1999): Subtropical counter-current in an idealized ocean GCM. J. Phys. Oceanogr., 29, 1303–1313.
Kuragano, T. and M. Kamachi (2000): Global statistical space-time scales of oceanic variability estimated from the TOPEX/POSEIDON altimeter data. J. Geophys. Res., 105, 955–974.
Kwon, Y.-O. and S. C. Riser (2004): North Atlantic Subtropical Mode Water: A history of ocean-atmosphere interaction 1961–2000. Geophys. Res. Lett., 31, L19307, doi:10.1029/2004GL021116.
Masuzawa, J. (1969): Subtropical Mode Water. Deep-Sea Res., 16, 463–472.
Mizuno, K. and W. B. White (1983): Annual and interannual variability in the Kuroshio Current System. J. Phys. Oceanogr., 13, 1847–1867.
Nishikawa, S. and A. Kubokawa (2007): Mixed layer depth front and subduction of low potential vorticity water in an idealized ocean GCM. J. Oceanogr., 63, 125–134.
Oka, E. and T. Suga (2003): Formation region of North Pacific subtropical mode water in the late winter of 2003. Geophys. Res. Lett., 30, 2205, doi:10.1029/2003GL018581.
Oka, E., T. Suga and L. D. Talley (2007): Temporal variability of winter mixed layer in the mid-to high-latitude North Pacific. J. Oceanogr., 63, 293–307.
Qiu, B. (2002): The Kuroshio Extension system: Its large-scale variability and role in the midlatitude ocean-atmosphere interaction. J. Oceanogr., 58, 57–75.
Qiu, B. and S. Chen (2005): Variability of the Kuroshio Extension jet, recirculation gyre and mesoscale eddies on decadal timescales. J. Phys. Oceanogr., 35, 2090–2103.
Qiu, B. and S. Chen (2006): Decadal variability in the formation of the North Pacific Subtropical Mode Water: Oceanic versus atmospheric control. J. Phys. Oceanogr., 36, 1365–1380.
Qiu, B., P. Hacker, S. Chen, K. A. Donohue, D. R. Watts, H. Mitsudera, N. G. Hogg and S. R. Jayne (2006): Observations of the Subtropical Mode Water evolution from the Kuroshio Extension System Study. J. Phys. Oceanogr., 36, 457–473.
Qiu, B., S. Chen and P. Hacker (2007): Effect of mesoscale eddies on subtropical mode water variability from the Kuroshio Extension System Study (KESS). J. Phys. Oceanogr., 37, 982–1000.
Rainville, L., S. R. Jayne, J. L. McClean and M. E. Maltrud (2007): Formation of subtropical mode water in a high-resolution ocean simulation of the Kuroshio Extension region. Ocean Modell., 17, 338–356.
Roemmich, D., J. Gilson, R. Davis, P. Sutton, S. Wijffels and S. Riser (2007): Decadal spinup of the South Pacific subtropical gyre. J. Phys. Oceanogr., 37, 162–173.
Suga, T. and K. Hanawa (1990): The mixed layer climatology in the northwestern part of the North Pacific subtropical gyre and the formation area of Subtropical Mode Water. J. Mar. Res., 48, 543–566.
Suga, T. and K. Hanawa (1995a): The subtropical mode water circulation in the North Pacific. J. Phys. Oceanogr., 25, 958–970.
Suga, T. and K. Hanawa (1995b): Interannual variations of North Pacific Subtropical Mode Water in the 137°E section. J. Phys. Oceanogr., 25, 1012–1017.
Suga, T., K. Hanawa and Y. Toba (1989): Subtropical mode water in the 137°E section. J. Phys. Oceanogr., 19, 1605–1618.
Suga, T., K. Motoki, Y. Aoki and A. M. Macdonald (2004): The North Pacific climatology of winter mixed layer and mode waters. J. Phys. Oceanogr., 34, 3–22.
Sugimoto, S. and K. Hanawa (2005): Remote reemergence areas of winter sea surface temperature anomalies in the North Pacific. Geophys. Res. Lett., 32, L01606, doi:10.1029/2004GL021410.
Taneda, T., T. Suga and K. Hanawa (2000): Subtropical mode water variation in the southwestern part of the North Pacific subtropical gyre. J. Geophys. Res., 105, 19591–19598.
Uehara, H., T. Suga, K. Hanawa and N. Shikama (2003): A role of eddies in formation and transport of North Pacific Subtropical Mode Water. Geophys. Res. Lett., 30, 1705, doi:10.1029/2003GL017542.
Yasuda, T. and K. Hanawa (1997): Decadal changes in the mode waters in the midlatitude North Pacific. J. Phys. Oceanogr., 27, 858–870.
Yasuda, T. and K. Hanawa (1999): Composite analysis of North Pacific subtropical mode water properties with respect to the strength of the wintertime East Asian monsoon. J. Oceanogr., 55, 531–541.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Oka, E. Seasonal and interannual variation of North Pacific Subtropical Mode Water in 2003–2006. J Oceanogr 65, 151–164 (2009). https://doi.org/10.1007/s10872-009-0015-y
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10872-009-0015-y