Abstract
We survey the recent progress in studies of North Pacific Intermediate Water (NPIW) in SAGE (SubArctic Gyre Experiment), including important results obtained from related projects. Intensive observations have provided the transport distributions relating to NPIW and revealed the existence of the cross-wind-driven gyre Oyashio water transport that flows directly from the subarctic to subtropical gyres through the western boundary current as well as the diffusive contribution across the subarctic front. The anthropogenic CO2 transport into NPIW has been estimated. The northern part of NPIW in the Transition Domain east of Japan is transported to the Gulf of Alaska, feeding the mesothermal (intermediate temperature maximum) structure in the North Pacific subarctic region where deep convection is restricted by the strong halocline maintained by the warm and salty water transport originating from NPIW. This heat and salt transport is mostly balanced by the cooling and freshening in the formation of dense shelf water accompanied by sea-ice formation and convection in the Okhotsk Sea. Intensive observational and modeling studies have substantially altered our view of the intermediate-depth circulation in the North Pacific. NPIW circulations are related to diapycnal-meridional overturning, generated around the Okhotsk Sea due to tide-induced diapycnal mixing and dense shelf water formation accompanied by sea-ice formation in the Okhotsk Sea. This overturning circulation may possibly explain the direct cross-gyre transport through the Oyashio along the western boundary from the subarctic to subtropical gyres.
Similar content being viewed by others
References
Alfultis, M. A. and S. Martin (1987): Satellite passive microwave studies of the Sea of Okhotsk ice cover and its relation to oceanic processes, 1978-1982. J. Geophys. Res., 92, 13013–13028.
Andreev, A., M. Honda, Y. Kuramoto, M. Kusakabe and A. Murata (2001): Excess CO2 and pHexcess in the intermediate water layer of the northwestern Pacific. J. Oceanogr., 57, 177–188.
Favorite, F., A. J. Dodimead and K. Nasu (1976): Oceanography of the Subarctic Pacific region, 1960-71. Bull. Int. North Pacific Comm., 33, 1–187.
Hasunuma, K. (1978): Formation of the intermediate salinity minimum in the northwestern Pacific Ocean. Bull. Ocean Res. Inst., Univ. of Tokyo, 9, 47 pp.
Hiroe, Y., I. Yasuda, K. Komatsu, K. Kawasaki, T. M. Joyce and F. Bahr (2002): Transport of the North Pacific Intermediate Water in the Kuroshio-Oyashio Interfrontal zone. Deep-Sea Res. II, 49, 5353–5364.
Inoue, R., J. Yoshida, Y. Hiroe, K. Komatsu, K. Kawasaki and I. Yasuda (2003): Modification of North Pacific Intermediate Water around Mixed Water Region. J. Oceanogr., 59, 211–224.
Ishizaki, H. and I. Ishikawa (2004): Simulation of formation and spreading of salinity minimum associated with NPIW using a high-resolution model. J. Oceanogr., 60, this issue, 463–485.
Isoda, Y., S. Shimizu, T. Izawa and T. Azumaya (2002): Interannual variations of North Pacific Intermediate Water across 150?E and 180??sections in the subarctic North Pacific. Umi to Sora, 77, 143–151 (in Japanese with English abstract).
Ito, S., K. Uehara, T. Miyao, H. Miyake, I. Yasuda, T. Watanabe and Y. Shimizu (2004): Characteristics of SSH anomaly based on TOPEX/POSEIDON altimetery and in situmeasured velocity and transport of Oyashio on OICE. J. Oceanogr., 60, this issue, 425–437.
Itoh, M. (2000): Formation and distribution of Okhotsk Sea Intermediate Water. Ph.D. Thesis of Environmental Earth Science, Hokkaido Univ., 62 pp.
Itoh, M., K. I. Ohshima and M. Wakatsuchi (2003): Formation and distribution of Okhotsk Sea Intermediate Water: an analysis of climatological data. J. Geophys. Res., 108(C8), art.-no.3258
Iwao, T., M. Endoh, N. Shikama and T. Nakano (2003): Intermediate circulation in the northwestern North Pacific derived from subsurface floats. J. Oceanogr., 59, 893–904.
Joyce, T. M. and J. Dunworth-Baker (2003): Long-term hydrographic variability in the Northwest Pacific Ocean. Geophys. Res. Lett., 30(2), 1043, doi:10.1029/ 2002GL015225.
Joyce, T. M., I. Yasuda, Y. Hiroe, K. Komatsu, K. Kawasaki and F. Bahr (2001): Mixing in the meandering Kuroshio Extension and the formation of NPIW. J. Geophys. Res., 106, 4397–4407.
Kaneko, I., Y. Takatsuki and H. Kamiya (2001): Circulation of intermediate and deep waters in the Philippine Sea. J. Oceanogr., 57, 397–420.
Katsumata, K., I. Yasuda and Y. Kawasaki (2001): Direct current measurements in Krusensterna Strait in summer. Geophys. Res. Lett., 28, 319–322.
Katsumata, K., K.-I. Ohshima, T. Kono, M. Itoh, I. Yasuda and M. Wakatsuchi (2003): Water exchange and tidal currents through the Bussol Strait revealed by direct current measurements. J. Geophys. Res. (submitted).
Kawasaki, Y. (1999): On the year-to-year change in subarctic water characteristics around the Kuril Islands. PICES Sci. Rep., 12, 101–106.
Kawasaki, Y. and A. Kusaka (2003): Long-term variations in subarctic water masses. J. Oceanogr. (submitted).
Kitani, K. (1973): An oceanographic study of the Okhotsk Sea-particularly in regard to cold waters. Bull. Far Seas Fish. Res. Lab., 9, 45–76.
Komatsu, K., Y. Hiroe, I. Yasuda, K. Kawasaki, T. M. Joyce and F. Bahr (2004): Hydrographic structure and transport of intermediate water in the Kuroshio region off the Boso Peninsula, Japan. J. Oceanogr., 60, this issue, 487–503.
Kono, T. (1997): Modification of the Oyashio Water in the Hokkaido and Tohoku Area. Deep-Sea Res., 44, 669–688.
Kono, T. and Y. Kawasaki (1997a): Modification of the western subarctic water by exchange with the Okhotsk Sea. Deep-Sea Res., 44, 689–711.
Kono, T. and Y. Kawasaki (1997b): Results of CTD and mooring observations southeast of Hokkaido 1. Annual velocity and transport variations in the Oyashio. Bull. Hokkaido Natl. Fish. Res. Inst., 61, 65–81.
Kono, T. and Y. Kawasaki (1997c): Results of CTD and mooring observations southeast of Hokkaido 2. Annual variations of water mass structure and salt flux of the Oyashio. Bull. Hokkaido Natl. Fish. Res. Inst., 61, 83–95.
Kono, T., S. C. Riser, T. Takizawa, Y. Kawasaki and M. Wakatsuchi (2001): Formation process of the Oyashio water from the mooring observations in the Bussol' Strait. p. 6–7. In Proc. of Int. Symp. on Atmosphere-Ocean-Cryosphere Interaction in the Sea of Okhotsk and Surrounding Environment, Hokkaido Univ., Japan.
Kouketsu, S., I. Yasuda and Y. Hiroe (2004): Formation process of North Pacific Intermediate Water around the Kuroshio Extension with High-resolution observation. J. Geophys. Res. (in preparation).
Kusaka, A., S. Ito, K. Uehara, T. Kono and Y. Kawasaki (2003): Seasonal variation of the Oyashio volume transport southeast of Hokkaido, Japan. J. Oceanogr. (submitted).
Martin, S., R. Drucker and K. Yamashita (1998): The production of ice and dense shelf water in the Okhotsk Sea polynyas. J. Geophys. Res., 103, 27771–27782.
Masujima, M., I. Yasuda, Y. Hiroe and T. Watanabe (2003): Transport of Oyashio water across the Subarctic Front into the Mixed Water Region and formation of NPIW. J. Oceanogr., 59, 855–869.
Miura, T., T. Suga and K. Hanawa (2002): Winter mixed layer and formation of dichothermal water in the Bering Sea. J. Oceanogr., 58, 815–823.
Miura, T., T. Suga and K. Hanawa (2003): Numerical study on formation of the dichothermal water in the Bering Sea. J. Oceanogr., 59, 369–376.
Miyao, T. and K. Ishikawa (2003): Formation, distribution and volume transport of the North Pacific Intermediate Water studied by repeat hydrographic observations. J. Oceanogr., 59, 905–919.
Nakamura, T. and T. Awaji (2003): Tidally induced diapycnal mixing in the Kuril Starits and the roles on water transformation and transport processes. J. Geophys. Res. (submitted).
Nakamura, T., T. Awaji, T. Hatayama, K. Akitomo and T. Takizawa (2000a): Tidal exchange through the Kuril Straits. J. Phys. Oceanogr., 30, 1622–1644.
Nakamura, T., T. Awaji, T. Hatayama, K. Akitomo, T. Takizawa, T. Kono and M. Fukazawa (2000b): The generation of largeamplitude unsteady lee waves by subinertial K1 tidal flow: A possible vertical mixing mechanism in the Kuril Straits. J. Phys. Oceanogr., 30, 1601–1621.
Nakamura, T., T. Toyoda, Y. Ishikawa and T. Awaji (2004): Tidal mixing in the Kuril Straits and its impact on ventilation in the North Pacific Ocean. J. Oceanogr., 60, this issue, 411–423.
Ohshima, K-I., M. Wakatsuchi, Y. Fukamachi and G. Mizuta (2002): Near-surface circulation and tidal currents of the Okhotsk Sea observed with the satellite-tracked drifters. J. Geophys. Res., 107(C11), art.no.-3195 Nov.2002
Okuda, K., I. Yasuda, Y. Hiroe and Y. Shimizu (2001): Structure of subsurface intrusion of the Oyashio water into the Kuroshio Extension and formation process of the North Pacific Intermediate Water. J. Oceanogr., 57, 121–140.
Ono, T., Y. W. Watanabe and K. Sasaki (2000): Annual anthropogenic carbon transport into the North Pacific Intermediate Water through the Kuroshio/Oyashio interfrontal zone: An estimation from CFCs distribution. J. Oceanogr., 56, 675–689.
Ono, T., T. Midorikawa, Y. W. Watanabe, K. Tadokoro and T. Saino (2001): Temporal increase of phosphate and apparent oxygen utilization in the subsurface waters of western subarctic Pacific from 1968 to 1998. Geophys. Res. Lett., 28, 3285–3288.
Ono, T., K. Sasaki and I. Yasuda (2003): Re-estimation of annual anthropogenic carbon input from Oyashio into North Pacific Intermediate Water. J. Oceanogr., 59, 883–891.
Reid, J. L., Jr. (1965): Intermediate waters of the Pacific Ocean. The Johns Hopkins Oceanographic Studies, 5, 96 pp.
Reid, J. L., Jr. (1997): On the total geostrophic circulation of the Pacific ocean: Flow patters, tracers, and transports. Prog. Oceanogr., 39, 263–352.
Riser, S. C. (2001): The exchange of water between the Okhotsk Sea and the North Pacific Ocean, and implication to intermediate water formation. p. 2–3. In Proc. of Int. Symp. on Atmosphere-Ocean-Cryosphere Interaction in the Sea of Okhotsk and Surrounding Environment, Hokkaido Univ., Japan.
Rogachev, K. A. (2000): Recent variability in the Pacific western subarctic boundary currents and Sea of Okhotsk. Prog. Oceanogr., 47, 299–336.
Sabine, C. L., R. A. Feely, R. M. Key, J. L. Bullister, F. J. Millero, K. Lee, T. H. Peng, B. Tilbrook, T. Ono and C. S. Wong (2002): Distribution of anthropogenic CO2 in the Pacific Ocean. Global Biogeochem. Cycles, 16, art.no.-1083.
Shimizu, Y., I. Yasuda and S. Ito (2001): Distribution and circulation of the coastal Oyashio intrusion. J. Phys. Oceanogr., 31, 1561–1578.
Shimizu, Y., I. Yasuda, K. Okuda, K. Hanawa and S. Ito (2003): ADCP-referenced Kuroshio and Oyashio water transports for the North Pacific Intermediate Water formation. J. Phys. Oceanogr., 33, 220–233.
Shimizu, Y., T. Iwao, I. Yasuda, S. Ito, T. Watanabe, K. Uehara, N. Shikama and T. Nakano (2004): Formation process of North Pacific Intermediate Water revealed by profiling floats set to drift on 26.7 ???isopycnal surface. J. Oceanogr., 60, this issue, 453–462.
Stommel, H. and A. B. Arons (1960): On the abyssal circulation of the world ocean. I. Stationary planetary flow patterns on a sphere. Deep-Sea Res., 6, 140–154.
Sverdrup, H., M. W. Johnson and R. H. Fleming (1942): The Oceans, Their Physics, Chemistry, and Biology. Prentice-Hall, 1087 pp.
Talley, L. D. (1991): An Okhotsk Sea anomaly: Implication for ventilation in the North Pacific. Deep-Sea Res., 38(Suppl.), S171–S190.
Talley, L. D. (1993): Distribution and formation of North Pacific Intermediate Water. J. Phys. Oceanogr., 23, 517–537.
Talley, L. D. (1997): North Pacific Intermediate Water transports in the mixed water region. J. Phys. Oceanogr., 27, 1795–1803.
Talley, L. D. and J.-Y. Yun (2001): Cabbeling, double diffusion and density of North Pacific Intermediate Water. J. Phys. Oceanogr., 31, 1538–1549.
Talley, L. D., Y. Nagata, M. Fujimura, T. Kono, D. Inagake, M. Hirai and K. Okuda (1995): North Pacific Intermediate Water in the Kuroshio/Oyashio mixed water region. J. Phys. Oceanogr., 25, 475–501.
Tatebe, H. (2003): Numerical studies on the Oyashio southward intrusion and associated cross-gyre transport. Ph.D. Thesis of Graduate School of Science, Univ. of Tokyo, 91 pp.
Tatebe, H. and I. Yasuda (2003): The Oyashio southward intrusion and cross-gyre transport related to diapycnal upwelling in the Okhotsk Sea. J. Phys. Oceanogr. (submitted).
Uda, M. (1963): Oceanography of the subarctic Pacific Ocean. J. Fish. Res. Board Canada, 20, 119–179.
Uehara, K., S. Ito, H. Miyake, I. Yasuda, Y. Shimizu and T. Watanabe (2004): Absolute volume transports of the Oyashio referred to moored current meter data crossing the OICE. J. Oceanogr., 60, this issue, 397–409.
Ueno, H. and I. Yasuda (2000): Distribution and formation of the mesothermal structure (temperature inversions) in the North Pacific subarctic region. J. Geophys. Res., 105, 16,885-16,897.
Ueno, H. and I. Yasuda (2001): Warm and saline water transport to the North Pacific subarctic region: World Ocean Circulation Experiment and Subarctic Gyre Experiment data analysis. J. Geophys. Res., 106, 22,131–22,141.
Ueno, H. and I. Yasuda (2003): Intermediate water circulation in the North Pacific subarctic and northern subtropical regions. J. Geophys. Res., 108(C11), 3348, doi:10.1029/ 2002JC001372.
Watanabe, T. and M. Wakatsuchi (1998): Formation of 26.8-26.9 ???water in the Kuril Basin of the Sea of Okhotsk as a possible origin of North Pacific Intermediate Water. J. Geophys. Res., 103, 2849–2865.
Watanabe, Y. W., T. Ono, A. Shimamoto, T. Sugimoto, M. Wakita and S. Watanabe (2001): Probability of a reduction in the formation rate of the subsurface water in the North Pacific during 1980s and 1990s. Geophys. Res. Lett., 28, 3289–3292.
Wong, A. P. S., N. L. Bindoff and J. A. Church (1999): Largefreshening of intermediate waters in the Pacific and Indian Oceans. Nature, 400, 440–443.
Wüst, G. (1930): —Meridionale Schichtung und Tiefenzirkulation in den Westhalfen der drei Ozeane. J. du Cons. Int'l. pour l'Expl. de la Mer, 5(1), 21 pp.
Yamamoto, M. (2001): Formation of the Okhotsk Sea Intermediate Water clarified with chemical tracers. Ph.D. Thesis, Graduate School of Environmental Earth Science, Hokkaido Univ., 104 pp.
Yamamoto, M., N. Tanaka and S. Tsunogai (2001): Okhotsk Sea Intermediate Water formation deduced from oxygen isotope systematics. J. Geophys. Res., 106, 31075–31084.
Yamamoto, M., S. Watanabe, S. Tsunogai and M. Wakatsuchi (2002): Effects of sea ice formation and diapycnal mixing on the Okhotsk Sea Intermediate Water clarified with oxygen isotope. Deep-Sea Res., 49, 1165–1174.
Yasuda, I. (1997): The origin of the North Pacific Intermediate Water. J. Geophys. Res., 102, 893–909.
Yasuda, I. (2003): Hydrographic structure and variability of the Kuroshio-Oyashio Transition Area. J. Oceanogr., 59, 389–402.
Yasuda, I., K. Okuda and Y. Shimizu (1996): Distribution and modification of the North Pacific Intermediate Water in the Kuroshio-Oyashio Interfrontal zone. J. Phys. Oceanogr., 26, 448–465.
Yasuda, I., S. Ito, Y. Shimizu, K. Ichikawa, K. Ueda, T. Honma, M. Uchiyama, K. Watanabe, T. Suno, K. Tanaka and K. Koizumi (2000): Cold-core anti-cyclonic eddies south of the Bussol' Strait in the north-western Subarctic Pacific. J. Phys. Oceanogr., 30, 1137–1157.
Yasuda, I., Y. Hiroe, K. Komatsu, K. Kawasaki, T. M. Joyce, F. Bahr and Y. Kawasaki (2001): Hydrographic structure and transport of the Oyashio south of Hokkaido and the formation of the North Pacific Intermediate Water. J. Geophys. Res., 106, 6931–6942.
Yasuda, I., S. Kouketsu, K. Katsumata, M. Ohiwa, Y. Kawasaki and A. Kusaka (2002): Influence of intermediate Okhotsk Sea water on the Oyashio and North Pacific Intermediate Water. J. Geophys. Res., 107, doi:10.1029/2001JC001037.
Yoshinari, H., I. Yasuda, S. Ito, E. Firing, Y. Matsuo, O. Kato and Y. Shimizu (2001): Meridional transport of the North Pacific Intermediate Water in the Kuroshio-Oyashio interfrontal zone. Geophys. Res. Lett., 28, 3445–3448.
Yoshinari, H., I. Yasuda and M. Ikeda (2003): Meridional transport of North Pacific Intermediate Water across 37?N based on an objective analysis of Lowered Acoustic Doppler Current Profiler data. J. Geophys. Res. (in press).
You, Y., N. Suginohara, M. Fukasawa, I. Yasuda, I. Kaneko, H. Yoritaka and M. Kawamiya (2000): Roles of the Okhotsk Sea and Gulf of Alaska in forming the North Pacific Intermediate Water. J. Geophys. Res., 105, 3253–3280.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Yasuda, I. North Pacific Intermediate Water: Progress in SAGE (SubArctic Gyre Experiment) and Related Projects. Journal of Oceanography 60, 385–395 (2004). https://doi.org/10.1023/B:JOCE.0000038344.25081.42
Issue Date:
DOI: https://doi.org/10.1023/B:JOCE.0000038344.25081.42