Intraseasonal-to-Interannual Variability of the Upper-Layer Zonal Currents in the Tropical Northwest Pacific Ocean

  • Fuad Azminuddin
  • Dongchull JeonEmail author
  • Chang-Woong Shin


The upper-layer circulation in the Tropical Northwest Pacific Ocean (TNWP) is characterized by the alternating zonal currents, such as North Equatorial Current (NEC) and Subtropical Countercurrent (STCC). The variabilities of the upper-layer zonal currents in the TNWP, which were obtained directly from 75 kHz acoustic Doppler current profiler (ADCP) measurements and indirectly from geostrophic calculations, were investigated on intraseasonal to interannual timescales from 2006 to 2014. Surface geostrophic current derived from sea surface height anomaly (SSHA) approximated well to the in-situ measurements with ADCP that was slightly better than the absolute geostrophic current obtained from AVISO. The interannual signals related to the El Niño-Southern Oscillation (ENSO) were quite apparent, especially near the boundary (about 17.5°N–19°N) between NEC and STCC. We found that the eastward-flowing southern STCC develops during the decaying phase of ENSO and weakens during La Niña. Strong easterlies during strong La Niña (e.g., 2010 La Niña event) seem to influence NEC to expand further north to the southern STCC region and this coincides with the meridional migration of the Sverdrup streamfunction. The southern STCC region is profoundly influenced by the mesoscale/sub-mesoscale eddy activities, which can intensify the eastward flow of STCC and ultimately contribute to the intraseasonal signal. We found that this intraseasonal signal weakened when La Niña happened in 2010, which is presumably associated with the northward expansion of NEC. Possible factors related to the discrepancies between surface geostrophic current and sub-surface ADCP data are discussed.


ADCP measurements zonal currents intraseasonal-to-interannual variability ENSO mesoscale eddies 


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  1. AVISO (2009) SSALTO/DUACS user handbook: (M)SLA and (M)ADT near-real time and delayed time products. CLSDOS- NT-06.034Google Scholar
  2. Chen X, Qiu B, Chen S, Qi Y, Du Y (2015) Seasonal eddy kinetic energy modulations along the North Equatorial Countercurrent in the western Pacific. J Geophys Res-Oceans 120:6351–6362. doi:10.1002/2015JC011054CrossRefGoogle Scholar
  3. Fine RA, Lukas R, Bingham FM, Warner MJ, Gammon RH (1994) The western equatorial Pacific: a water mass crossroads. J Geophys Res 99:25063–25080. doi:10.1029/94JC02277CrossRefGoogle Scholar
  4. Harrison DE, Vecchi GA (1999) On the termination of El Niño. Geophys Res Lett 11:1593–1596CrossRefGoogle Scholar
  5. Hu D, Cui M (1991) The western boundary current of the Pacific and its role in the climate. Chin J Oceanol Limn 9:1–14. doi:10.1007/BF02849784CrossRefGoogle Scholar
  6. Hu D, Wang F, Wu L, Chen D, Liu Q, Tian J (2011) Northwestern Pacific Ocean Circulation and Climate Experiment (NPOCE). pChina Ocean Press, BeijingGoogle Scholar
  7. Hu D, Wu L, Cai W, Gupta AS, Ganachaud A, Qiu B, Gordong AL, Lin X, Chen Z, Hu S, Wang G, Wang Q, Sprintall J, Qu T, Kashino Y, Wang F, Kessler WS (2015) Pacific western boundary currents and their roles in climate. Nature 522:299–308. doi:10.1038/nature14504CrossRefGoogle Scholar
  8. Hu S, Hu D (2014) Variability of the Pacific North Equatorial Current from repeated shipboard acoustic Doppler current profiler measurements. J Oceanogr 70:559–571. doi:10.1007/s10872-014-0253-5CrossRefGoogle Scholar
  9. Hu S, Hu D, Guan C, Wang F, Zhang L, Wang F, Wang Q (2016) Interannual variability of the Mindanao Current/Undercurrent in direct observations and numerical simulations. J Phys Oceanogr 46:483–499. doi:10.1175/JPO-D-15-0092.1CrossRefGoogle Scholar
  10. JTWC (2007) Annual tropical cyclone report. Joint Typhoon Warning Center (JTWC). Accessed 8 Mar 2017
  11. JTWC (2008) Annual tropical cyclone report. Joint Typhoon Warning Center (JTWC). Accessed 8 Mar 2017
  12. Kim E, Jeon D, Shin CW, Kim DG (2014) Variation of the southern Subtropical Countercurrent related to sea surface height and eddies in the northwest tropical Pacific. Ocean Sci J 49(1): 35–46CrossRefGoogle Scholar
  13. KIOST (2014) Northwestern Pacific Ocean study on environment and interactions between deep ocean and marginal seas (POSEIDON). Korea Institute of Ocean Science and Technology, BSPE 99231-10618:59-61Google Scholar
  14. Kug JS, Kang IS (2003) Symmetric and antisymmetric mass exchanges between the equatorial and off-equatorial Pacific associated with ENSO. J Geophys Res 108:1–12. doi:10.1029/ 2002JC001671CrossRefGoogle Scholar
  15. Le Traon PY, Ogor F (1998) ERS-1/2 orbit improvement using TOPEX/Poseidon: the 2 cm challenge. J Geophys Res 103: 8045–8057CrossRefGoogle Scholar
  16. Le Traon PY, Nadal F, Ducet N (1998) An improved mapping method of multisatellite altimeter data. J Atmos Ocean Tech 15:522–534CrossRefGoogle Scholar
  17. Lehmann A, Hinrichsen HH (1995) A comparison of geostrophic velocities and profiling ADCP measurements in the Iberian Basin. J Atmos Ocean Tech 12:901–914CrossRefGoogle Scholar
  18. Priestley MB (1982) Spectral analysis and time series. Academic Press, San Diego, 890 pGoogle Scholar
  19. Poulain PM, Menna M, Mauri E (2011) Surface geostrophic circulation of the Mediterranean Sea derived from drifter and satellite altimeter data. J Phys Oceanogr 42:973–990. doi:10.1175/JPO-D-11-0159.1CrossRefGoogle Scholar
  20. Qiu B, Joyce TM (1992) Interannual variability in the mid-and lowlatitude western North Pacific. J Phys Oceanogr 22(9):1062–1079. doi:10.1175/1520-0485(1992)022<1062:IVITMA>2.0.CO;2CrossRefGoogle Scholar
  21. 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 101:12315–12330. doi:10.1029/95JC03204CrossRefGoogle Scholar
  22. Qiu B, Chen S, Klein P, Sasaki H, Sasai Y (2014) Seasonal mesoscale and submesoscale eddy variability along the North Pacific Subtropical Countercurrent. J Phys Oceanogr 44:3079–3098. doi:10.1175/JPO-D-14-0071.1CrossRefGoogle Scholar
  23. Schlitzer R (2018) Ocean Data View. Accessed 18 May 2018Google Scholar
  24. Toole J, Millard R, Wang Z, Pu S (1990) Observations of the Pacific North Equatorial Current bifurcation at the Philippine coast. J Phys Oceanogr 20(2):307–318. doi:10.1175/1520-0485(1990)020<0307:OOTPNE>2.0.CO;2CrossRefGoogle Scholar
  25. Ueki I, Kashino Y, Kuroda Y (2003) Observation of current variations off the New Guinea coast including the 1997–1998 El Niño period and their relationship with Sverdrup transport. J Geophys Res 108:3243. doi:10.1029/2002JC001611CrossRefGoogle Scholar
  26. Wang F, Li Y, Wang J (2016) Intraseasonal variability of the surface zonal currents in the western tropical Pacific Ocean: characteristics and mechanisms. J Phys Oceanogr 46:3639–3660. doi:10.1175/ JPO-D-16-0033.1CrossRefGoogle Scholar
  27. Yaremchuk M, Qu T (2003) Seasonal variability of the large-scale currents near the coast of the Philippines. J Phys Oceanogr 34:844–855CrossRefGoogle Scholar
  28. Zhai F, Hu D (2013) Revisit the interannual variability of the North Equatorial Current transport with ECMWF ORA-S3. J Geophys Res 118(3):1349–1366. doi:10.1002/jgrc.20093CrossRefGoogle Scholar
  29. Zhang L, Wang FJ, Wang Q, Hu S, Wang F, Hu D (2017) Structure and variability of the North Equatorial Current/Undercurrent from mooring measurements at 130°E in the Western Pacific. Sci Rep 7:46310. doi:10.1038/srep46310CrossRefGoogle Scholar

Copyright information

© Korea Institute of Ocean Science & Technology (KIOST) and the Korean Society of Oceanography (KSO) and Springer Nature B.V. 2019

Authors and Affiliations

  • Fuad Azminuddin
    • 1
    • 2
  • Dongchull Jeon
    • 1
    • 2
    Email author
  • Chang-Woong Shin
    • 1
  1. 1.Ocean Circulation and Climate Research Center, KIOSTBusanKorea
  2. 2.Department of Integrated Ocean SciencesUniversity of Science and TechnologyDaejeonKorea

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