Ocean Dynamics

, Volume 68, Issue 9, pp 1109–1119 | Cite as

Targeted observation analysis of a Northwestern Tropical Pacific Ocean mooring array using an ensemble-based method

  • Danian Liu
  • Jiang Zhu
  • Yeqiang Shu
  • Dongxiao Wang
  • Weiqiang Wang
  • Changxiang Yan
  • Wei Zhou


An important supplement for ocean observing systems, the Northwestern Tropical Pacific Ocean (NWTPO) mooring array including 15 moorings equipped with Acoustic Doppler Current Profilers (ADCP) devices was developed by the Chinese Academy of Sciences and deployed in 2013. This study assessed the performance of this mooring array in monitoring the intra-seasonal and low-frequency (above 91 days) variability of oceanic currents by conducting targeted observation analyses using an ensemble-based method. Key regions for monitoring intra-seasonal variability of the NWTPO circulation are the equator, Indonesian throughflow (ITF), headstream of the North Equatorial Countercurrent (NECC), and Subtropical Countercurrent (STCC). For monitoring intra-seasonal variability, the range of each mooring is confined to a local scale. Therefore, NWTPO moorings cannot adequately resolve intra-seasonal variability in areas of the ITF, the headstream of the NECC, and STCC due to location constraints of the moorings. For monitoring low-frequency variability of NWTPO circulation, the key regions are the Western Boundary Current (WBC), NECC, and the Equatorial Undercurrent (EUC). NWTPO moorings performed relatively well in monitoring the low-frequency variability, as indicated by the strong background correlations between each of the currents. The NWTPO mooring array plays an important role in monitoring the location and intensity of background currents. Because moorings are costly and require a high-density distribution for optimal performance, understanding the multi-timescale dynamical nature of the NWTPO current system is critical for the deploying future moorings in this region.


Targeted observation analysis Data assimilation Mooring array 


Funding information

This work was supported by the National Key Research and Development Program of China (No. 2016YFC1401702 and 2016YFC1401705), the “Strategic Priority Research Program” of the Chinese Academy of Sciences (No. XDA10010405), and the National Natural Science Foundation of China (No. 41521005 and 41506022), and was carried out at National Supercomputer Center in Tianjin, and the calculations were performed on TianHe-1 (A).


  1. Ancell B, Hakim GJ (2007) Comparing adjoint- and ensemble-sensitivity analysis with applications to observation targeting. Mon Weather Rev 135(12):4117–4134CrossRefGoogle Scholar
  2. Berliner LM, Lu ZQ, Snyder C (1999) Statistical design for adaptive weather observations. J Atmos Sci 56(15):2536–2552CrossRefGoogle Scholar
  3. Bishop CH, Toth Z (1999) Ensemble transformation and adaptive observations. J Atmos Sci 56(11):1748–1765CrossRefGoogle Scholar
  4. Bishop CH, Etherton BJ, Majumdar SJ (2001) Adaptive sampling with the ensemble transform Kalman filter. Part I:theoretical aspects. Mon Weather Rev 129(3):420–436CrossRefGoogle Scholar
  5. Deng Z, Tang Y, Zhou X (2009) The retrospective prediction of El Niño-southern oscillation from 1881 to 2000 by a hybrid coupled model: (I) sea surface temperature assimilation with ensemble Kalman filter. Clim Dyn 32(2–3):397–413CrossRefGoogle Scholar
  6. Deng Z, Tang Y, Wang G (2010) Assimilation of Argo temperature and salinity profiles using a bias-aware localized EnKF system for the Pacific Ocean. Ocean Model 35(3):187–205CrossRefGoogle Scholar
  7. Desroziers G, Berre L, Chapnik B, Poli P (2005) Diagnosis of observation, background and analysis error statistics in observation space. Quart J Roy Meteorol Soc 131(613):3385–3396CrossRefGoogle Scholar
  8. Evensen G (2003) The ensemble Kalman filter: theoretical formulation and practical implementation. Ocean Dyn 53(4):343–367CrossRefGoogle Scholar
  9. Fine RA, Lukas R, Bingham FM, Warner MJ, Gammon RH (1994) The western equatorial Pacific: a water mass crossroads. J Geophys Res 99(C12):25063–25080CrossRefGoogle Scholar
  10. Gordon AL (1986) Interocean exchange of thermocline water. J Geophys Res 91(C4):5037–5046CrossRefGoogle Scholar
  11. Gordon AL, Sprintallb J, Aken HMV, Susanto D, Wijffels S, Molcarde R, Ffieldf A, Pranowog W, Wirasantosag S (2010) The Indonesian Throughflow during 2004–2006 as observed by the INSTANT program. Dyn Atmos Oceans 50(2):115–128CrossRefGoogle Scholar
  12. Goswami BN, Ajaya Mohan RS (2001) Intraseasonal oscillations and interannual variability of the Indian summer monsoon. J Clim 14(4):1180–1198CrossRefGoogle Scholar
  13. Heron SF, Metzger EJ, Skirving WJ (2006) Seasonal variations of the ocean surface circulation in the vicinity of Palau. J Oceanogr 62(4):413–426. CrossRefGoogle Scholar
  14. Hu D, Wu l CW, Gupta AS, Ganachaud A, Qiu B, Gordon 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(7556):299–308CrossRefGoogle Scholar
  15. Kashino Y, Ishida A, Hosoda S (2009) Observed ocean variability in the Mindanao dome region [J]. J Phys Oceanogr 41(2):287–302CrossRefGoogle Scholar
  16. Kashino Y, Atmadipoera A, Kuroda Y, Lukijanto (2013) Observed features of the Halmahera and Mindanao eddies. J Geophys Res 118(12):6543–6560CrossRefGoogle Scholar
  17. Kessler WS (1990) Observations of long Rossby waves in the northern tropical Pacific. J Geophys Res 95(C4):5183–5217CrossRefGoogle Scholar
  18. Kessler WS, Mcphaden MJ, Weickmann KM (1995) Forcing of intraseasonal Kelvin waves in the equatorial Pacific. J Geophys Res 100(C6):10613–10631CrossRefGoogle Scholar
  19. Kim YY, Qu T, Jensen T, Miyama T, Mitsudera H, Kang HW, Ishida A (2004) Seasonal and interannual variations of the North Equatorial Current bifurcation in a high-resolution OGCM. J Geophys Res 109(C3):325–347CrossRefGoogle Scholar
  20. Legates DR, Willmott CJ (1990) Mean seasonal and spatial variability in gauge corrected, global precipitation[J]. Int J Climatol 10(2):111–127CrossRefGoogle Scholar
  21. Li Y, Peng S, Liu D (2014) Adaptive observation in the South China Sea using CNOP approach based on a 3-D ocean circulation model and its adjoint model. J Geophys Res Oceans 119(12):8973–8986CrossRefGoogle Scholar
  22. Liu D, Shi P, Shu Y, Yao J, Wang D, Sun L (2016) Assimilating temperature and salinity profiles using ensemble Kalman filter with an adaptive observation error and T-S, constraint. Acta Oceanol Sin 35(1):30–37CrossRefGoogle Scholar
  23. Majumdar SJ (2016) A review of targeted observations. Bull Am Meteorol Soc 97(12):2287–2303CrossRefGoogle Scholar
  24. Masumoto Y, Yamagata T (1991) Response of the western tropical Pacific to the Asian winter monsoon: the generation of the Mindanao Dome. J Phys Oceanogr 21(9):1386–1398CrossRefGoogle Scholar
  25. Mu M, Zhou F, Wang H (2009) A method for identifying the sensitive areas in targeted observations for tropical cyclone prediction: conditional nonlinear optimal perturbation. Mon Weather Rev 137(5):1623–1639CrossRefGoogle Scholar
  26. Oke PR, Schiller AA (2007) Model-based assessment and design of a tropical Indian Ocean mooring array [J]. J Clim 20(13):3269–3283CrossRefGoogle Scholar
  27. Parent L, Testut CE, Brankart JM, Verron J, Brasseur P, Gourdeau L (2003) Comparative assimilation of topex/poseidon and ers altimeter data and of tao temperature data in the tropical pacific ocean during 1994–1998, and the mean sea-surface height issue. J Mar Syst 40(4):381–401CrossRefGoogle Scholar
  28. Qiu B (1999) Seasonal eddy field modulation of the North Pacific subtropical countercurrent: TOPEX/Poseidon observations and theory. J Phys Oceanogr 29(10):2471–2486CrossRefGoogle Scholar
  29. Qiu B, Joyce TM (1992) Interannual variability in the mid- and low-latitude western North Pacific. J Phys Oceanogr 22(9):1062–1079CrossRefGoogle Scholar
  30. 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):12315–12330CrossRefGoogle Scholar
  31. 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(12):3079–3098CrossRefGoogle Scholar
  32. Qiu B, Rudnick DL, Cerovecki I, Cornuelle BD, Chen S, Schönau MC, McClean JL, Copalakrishnan G (2015) The Pacific North Equatorial Current: new insights from the origins of the Kuroshio and Mindanao Currents (OKMC) project. Oceanogr 28(4):24–33CrossRefGoogle Scholar
  33. Qu T, Lukas R (2003) The bifurcation of the North Equatorial Current in the Pacific. J Phys Oceanogr 33(1):5–18CrossRefGoogle Scholar
  34. Sakov P, Oke PR (2008) Objective array design: application to the tropical indian ocean. J Atmos Ocean Technol 25(5):794–807CrossRefGoogle Scholar
  35. Schiller A, Wijffels SE, Sprintall J, Molcard R, Oke PR (2010) Pathways of intraseasonal variability in the Indonesian Throughflow region [J]. Dyn Atmos Oceans 50(2):174–200CrossRefGoogle Scholar
  36. Shao C, Xuan L, Cao Y, Cui X, Gao S (2015) Impact of Argo observation on the regional ocean reanalysis of China coastal waters and adjacent seas: a twin-experiment study. Adv Meteorol 2015:10): 1–10):15Google Scholar
  37. Tang Y, Kleeman R, Moore AM (2004) SST assimilation experiments in a tropical Pacific Ocean model. J Phys Oceanogr 34(34):623–642CrossRefGoogle Scholar
  38. Teague WJ, Carron MJ, Hogan PJ (1990) A comparison between the generalized digital environmental model and Levitus climatologies. J Geophys Res 95(C5):7167–7183CrossRefGoogle Scholar
  39. Tozuka T, Kagimoto T, Masumoto Y, Yamagata T (2002) Simulated multiscale variations in the western tropical Pacific: the Mindanao Dome revisited. J Phys Oceanogr 32(5):1338–1359CrossRefGoogle Scholar
  40. Wang F, Li Y, Wang J (2016a) Intraseasonal variability of the surface zonal currents in the western tropical Pacific Ocean: characteristics and mechanisms [J]. J Phys Oceanogr 46(12):3639–3660CrossRefGoogle Scholar
  41. Wang F, Wang J, Guan C, Ma Q, Zhang D (2016b) Mooring observation of equatorial currents over upper 1000 m depth in the western Pacific Ocean in 2014[J]. J Geophys Res Oceans 121(6):3730–3740CrossRefGoogle Scholar
  42. Webster PJ, Lukas R (1992) The tropical ocean/global: atmosphere Coupled Ocean-Atmosphere Response Experiments (COARE). Bull Am Meteorol Soc 73(9):1377–1416CrossRefGoogle Scholar
  43. Xie J, Zhu J (2010) Ensemble optimal interpolation schemes for assimilating Argo profiles into a hybrid coordinate ocean model. Ocean Model 33(3–4):283–298CrossRefGoogle Scholar
  44. Yan C, Zhu J, Zhou G (2007) Impacts of XBT, TAO, altimetry and ARGO observations on the tropical Pacific Ocean data assimilation [J]. Adv Atmos Sci 24(3):383–398CrossRefGoogle Scholar
  45. Yan C, Zhu J, Tanajura CAS (2015a) Impacts of mean dynamic topography on a regional ocean assimilation system. Ocean Sci 11(5):829–837CrossRefGoogle Scholar
  46. Yan C, Zhu J, Xie J (2015b) An ocean data assimilation system in the Indian Ocean and West Pacific Ocean. Adv Atmos Sci 32(11):1460–1472CrossRefGoogle Scholar
  47. Yu Z, McCreary JP, Kessler WS, Kelly KA (2000) Influence of equatorial dynamics on the Pacific north equatorial countercurrent. J Phys Oceanogr 30(12):3179–3190CrossRefGoogle Scholar
  48. Zhang C (2005) Madden-Julian oscillation. Rev Geophys 43(2):2528CrossRefGoogle Scholar
  49. Zhang Y, Xie Y, Wang H, Chen D, Toth Z (2016) Ensemble transform sensitivity method for adaptive observations. Adv Atmos Sci 33(1):10–20CrossRefGoogle Scholar
  50. Zhang X, Sun C, Liu C, Zhang L, Shao C, Zhang X, Zhao Y (2017) Evaluation of the impact of Argo data on ocean reanalysis in the pacific region. Adv Meteorol (c01015):1–12Google Scholar
  51. Zhao J, Li Y, Wang F (2013a) The role of mindanao dome in the variability of the Pacific North equatorial current bifurcation [J]. J Oceanogr 69(3):313–327CrossRefGoogle Scholar
  52. Zhao J, Li Y, Wang F (2013b) Dynamical responses of the West Pacific North Equatorial Countercurrent (NECC) system to El Niño events [J]. J Geophys Res Oceans 118(6):2828–2844CrossRefGoogle Scholar
  53. Zheng F, Zhu J, Zhang RH, Zhou GQ (2006) Ensemble hindcasts of SST anomalies in the tropical Pacific using an intermediate coupled model [J]. Geophys Res Lett 33(19):318–372CrossRefGoogle Scholar
  54. Zhou L, Murtugudde R (2010) Influences of Madden–Julian Oscillations on the eastern Indian Ocean and the maritime continent [J]. Dyn Atmos Oceans 50(2):257–274CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.State Key Laboratory of Tropical Oceanography, South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhouChina
  2. 2.University of Chinese Academy of SciencesBeijingChina
  3. 3.Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina

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