Ocean and Polar Research

Korea Institute of Ocean Science & Technology (한국해양과학기술원)
권호 표지
DOI QR코드

DOI QR Code

Interannual Variability of the Water Masses Observed in the Tropical Northwestern Pacific

북서태평양 열대해역에서 관측된 수괴의 경년변동성

  • Choi, Eunji (Integrated Ocean Sciences, Korea University of Science and Technology) ;
  • Jeon, Dongchull (Integrated Ocean Sciences, Korea University of Science and Technology)
  • 최은지 (과학기술연합대학원대학교 해양융합과학) ;
  • 전동철 (과학기술연합대학원대학교 해양융합과학)
  • Received : 2016.03.03
  • Accepted : 2016.05.15
  • Published : 2016.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

The interannual variability of the water masses was analyzed from the CTD data measured in the tropical northwestern Pacific from 2006 to 2014. There are two typical water masses NPTW and NPIW that reveal the interannual variability in the survey area, in addition to two other water masses; the surface water mass TSW with a large seasonal variability and the deep water mass AACDW with a constant temperature-salinity characteristic at the depths deeper than 2,000 meters. In 2012 and 2014 NPTW was the most widely extended horizontally and thicker than 100 meters vertically, which was found over the entire survey area. However, NPTW was reduced and became much narrower in 2009 than in the other years. NPIW seemed to expand southwards from the north of $21^{\circ}N$ to $15^{\circ}N$ in 2008 and in 2012, which showed the salinity minimum in 2013 (< 34.15 psu). The sea surface height estimated by Absolute Dynamic Topography (ADT) approximately along $135^{\circ}E$ section showed the high peaks (> $1.45dyn{\cdot}m$) between $16^{\circ}N$ and $18^{\circ}N$ during the periods between 2007 and 2009 and between 2012 and 2013; the former peak lasted wider and longer in latitude and time (about three times) than the latter. The vertical section of the geostrophic currents in the upper 1,000 meters shows that there was a mesoscale pattern of repeated eastward and westward flows a few times in some years (2010 and 2014), which seemed to disappear in some other years (2008 and 2012); the former was closely related to the mesoscale eddies and the latter implied the pattern with the permanent currents. The persistent eastward flow between $17^{\circ}N$ and $19^{\circ}N$ seems to be related to the Subtropical Countercurrent (STCC).

Keywords

References

  1. 김동국 (2006) 북서태평양 수온 연변동과 우리나라 기온과의 관계. 석사학위논문, 공주대학교, 60 p(Kim DG (2006) Relationship between interannual variation of the sea water temperature in the Western North Pacific and the temperature over Korea. MS Thesis, Kongju National University, Gongju, 60 p)
  2. 안중배, 류정희, 조익현, 박주영, 류상범 (1997) 한반도 기온 및 강수량과 적도 태평양 해면 온도와의 상관관계에 관한 연구. 한국기상학회지 33(3):487-495(Ahn JB, Ryu JH, Cho EH, Park JY, Ryoo SB (1997) A Study of correlations between air-temperature and precipitation in Korea and SST over the Tropical Pacific. J Korean Meteor Soc 33(3):487−495)
  3. CLS (2015) SSALTO/DUACS user handbook : (M)SLA and (M)ADT near-real time and delayed time products. CLSDOS-NT-06-034, SALP-MU-P-EA-21065-CLS. 66 p
  4. Fine RA, Lukas R, Bingham FM, Warner MJ, Gammon RH (1994) The western equatorial Pacific: a water mass crossroads. J Geophys Res 99(C12):25063-25080 https://doi.org/10.1029/94JC02277
  5. Lingling X, Jiwei T, Dunxin H, Fan W (2009) A quasisynoptic interpretation of water mass distribution and circulation in the western North Pacific: I. Water mass distribution. Chin J Oceanol Limn 27(3):630-639 https://doi.org/10.1007/s00343-009-9161-8
  6. Lukas R, Lindstrom E (1991) The Mixed Layer of the Western Equatorial Pacific Ocean. J Geophys Res 96(C01):3343-3357 https://doi.org/10.1029/90JC01951
  7. Lukas R, Yamagata T, McCreary JP (1996) Pacific lowlatitude western boundary currents and the Indonesian throughflow. J Geophys Res 101(C5):12209-12216 https://doi.org/10.1029/96JC01204
  8. Nakano T, Kitamura T, Sugimoto S, Suga T, Kamachi M (2015) Long-term variations of North Pacific Tropical Water along the $137^{\circ}E$ repeat hydrographic section. J Oceanogr 71(3):229-238 https://doi.org/10.1007/s10872-015-0279-3
  9. Nitani H (1972) Beginning of the Kuroshio. In: Stommel H and Yashida K (eds) Kuroshio: its physical aspects. University of Tokyo Press, Tokyo, pp 129-163
  10. Qiu B, Lukas R (1996) Seasonal and interannual variability of the North Equatorial Current, the Mindanao Current, and the Kuroshio along the Pacific western boundary. J Geophys Res 101(C5):12315-12330 https://doi.org/10.1029/95JC03204
  11. Qu T, Mitsudera H, Yamagata T (1999) A Climatology of the circulation and water mass distribution near the Philippine Coast. J Geophys Res 29(7):1488-1505
  12. Qu T, Mitsudera H, Yamagata T (2000) Intrusion of the North Pacific waters into the South China Sea. J Geophys Res 105(C3):6415-6424 https://doi.org/10.1029/1999JC900323
  13. Shimizu Y, Iwao T, Yasuda I, Ito S, Watanabe T, Uehara K, Shikama N, Nakano T (2004) Formation process on North Pacific intermediate water revealed by profiling floats set to drift on $26.7{\sigma}_{\theta}$ isopycnal surface. J Oceanogr 60(2):453-462 https://doi.org/10.1023/B:JOCE.0000038061.55914.eb
  14. Suga T, Kato A, Hanawa K (2000) North Pacific tropical water: its climatology and temporal changes associated with the climate regime shift in the 1970s. Prog Oceanog 47(2):223-256 https://doi.org/10.1016/S0079-6611(00)00037-9
  15. Talley LD (1993) Distribution and formation of North Pacific intermediate water. J Geophys Res 23(3):517-537
  16. Tsuchiya M (1968) Upper waters of the intertropical Pacific Ocean. The Johns Hopkins Press, Maryland, 50 p
  17. Wyrtki K (1961) Physical oceanography of the Southeast Asian waters. Scripps Institution of Oceanography, San Diego, 195 p