Advances in Atmospheric Sciences

, Volume 24, Issue 3, pp 383–398 | Cite as

Impacts of XBT, TAO, altimetry and ARGO observations on the tropical Pacific Ocean data assimilation

  • Yan Changxiang  (闫长香)
  • Zhu Jiang  (朱江)
  • Zhou Guangqing  (周广庆)


This study aims at assessing the relative impacts of four major components of the tropical Pacific Ocean observing system on assimilation of temperature and salinity fields. Observations were collected over a period between January 2001 through June 2003 including temperature data from the expendable bathythermographs (XBT), thermistor data from the Tropical Ocean Global Atmosphere Tropical Atmosphere-Ocean (TOGA-TAO) mooring array, sea level anomalies from the Topex/Poseidon and Jason-1 altimetry (T/P-J), and temperature and salinity profiles from the Array for Real-time Geostrophic Oceanography (ARGO) floats.

An efficient three-dimensional variational analysis-based method was introduced to assimilate the above data into the tropical-Pacific circulation model. To evaluate the impact of the individual component of the observing system, four observation system experiments were carried out. The experiment that assimilated all four components of the observing system was taken as the reference. The other three experiments were implemented by withholding one of the four components. Results show that the spatial distribution of the data influences its relative contribution. XBT observations produce the most distinguished effects on temperature analyses in the off-equatorial region due to the large amount of measurements and high quality. Similarly, the impact of TAO is dominant in the equatorial region due to the focus of the spatial distribution. The Topex/Poseidon-Jason-1 can be highly complementary where the XBT and TAO observations are sparse. The contribution of XBT or TAO on the assimilated salinity is made by the model dynamics because no salinity observations from them are assimilated. Therefore, T/P-J, as a main source for providing salinity data, has been shown to have greater impacts than either XBT or TAO on the salinity analysis. Although ARGO includes the subsurface observations, the relatively smaller number of observation makes it have the smallest contribution to the assimilation system.

Key words

data assimilation three-dimensional variational analysis sea level anomaly Array for Realtime Geostrophic Oceanography (ARGO) 


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  1. Alves, J. O. S., D. L. T. Anderson, and K. Haines, 2001: Sea level assimilation experiments in the tropical Pacific. J. Phys. Oceanogr., 31, 305–323.CrossRefGoogle Scholar
  2. Ando, K., and M. J. McPhaden, 1997: Variability of surface layer hydrography in the tropical Pacific. J. Geophys. Res., 102, 23 063–23 078.CrossRefGoogle Scholar
  3. Behringer, D. W., M. Ji, and A. Leetmaa, 1998: An improved coupled model for ENSO prediction and implications for ocean initialization. Part I: The ocean data assimilation system. Mon. Wea. Rev., 126, 1013–1021.CrossRefGoogle Scholar
  4. Bourassa, M. A., S. R. Smith, and J. J. O’Brien, 2001: A new FSU winds and flux climatology. 11th Conference on Interactions of the Sea and Atmosphere, San Diego, CA, Amer. Meteor. Soc., 912pp.Google Scholar
  5. Brusdal, K., J. Brankart, G. Halberstadt, G. Evensen, P. Brasseur, P. J. van Leeuwen, E. Dombrowsky, and J. Verron, 2003: An evaluation of ensemble based assimilation methods with a layered OGCM from the perspective of operational ocean forecasting systems. J. Mar. Sys., 40, 253–289.CrossRefGoogle Scholar
  6. Chen, D., M. A. Cane, S. E. Zebiak, and A. Kaplan, 1998: The impact of sea level data assimilation on the Lamont model prediction of the 1997/1998 El Niño. Geophys. Res. Lett., 25, 2837–2840.CrossRefGoogle Scholar
  7. Clancy, R. M., P. A. Phoebus, and K. D. Pollak, 1990: An operational global-scale ocean thermal analysis system. J. Atmos. Oceanic Technol., 7, 233–254.CrossRefGoogle Scholar
  8. Delcroix, T., C. Henin, V. Porte, and P. Arkin, 1996: Precipitation and sea surface salinity in the tropical Pacific Ocean. Deep-Sea Res. (Part I), 43, 1123–1141.CrossRefGoogle Scholar
  9. Derber, J. D., and A. Rosati, 1989: A global oceanic data assimilation system. J. Phys. Oceanogr., 19, 1333–1347.CrossRefGoogle Scholar
  10. Fischer, M., M. Latif, M. Flugel, and M. Ji, 1997: The impact of data assimilation on ENSO simulations and predictions. Mon. Wea. Rev., 125, 819–829.CrossRefGoogle Scholar
  11. Fujii, Y., and M. Kamachi, 2003: Three-dimensional analysis of temperature and salinity in the equatorial Pacific using a variational method with vertical coupled temperature-salinity empirical orthogonal function modes. J. Geophys. Res., 108(C9), doi:10.1029/2002JC001745.Google Scholar
  12. Fukumori, I., R. Raghunath, L. L. Fu, and Y. Chao, 1999: Assimilation of TOPEX/Poseidon altimeter data into a global ocean circulation model: How good are the results? J. Geophys. Res., 104, 25647–25665.CrossRefGoogle Scholar
  13. Fu Weiwei, Zhou Guangqing, and Wang Huijun, 2004: Ocean data assimilation with background error covariance derived from OGCM outputs. Adv. Atmos. Sci., 21(2), 181–192.Google Scholar
  14. Gill, A. E., and E. M. Rasmusson, 1983: The 1982/83 climate anomaly in the equatorial Pacific. Nature, 306, 229–234.CrossRefGoogle Scholar
  15. Haines, K., J. D. Blower, J. P. Drecourt, C. Liu, A. Vidard, I. Astin, and X. Zhou, 2006: Salinity assimilation using S(T): covariance relationship. Mon. Wea. Rev., 134, 759–771.CrossRefGoogle Scholar
  16. Hellerman, S., and M. Rosenstein, 1983: Normal monthly wind stress over the world ocean with error estimates. J. Phys. Oceanogr., 13, 1093–1104.CrossRefGoogle Scholar
  17. Henin, C., Y. du Penhoat, and M. Ioulalen, 1998: Observations of sea surface salinity in the western Pacific fresh pool: Large-scale changes in 1992–1995. J. Geophys. Res., 103, 7523–7536.CrossRefGoogle Scholar
  18. Hirose, N., I. Fukumori, C.-H. Kim, and J.-H. Yoon, 2005: Numerical simulation and satellite altimeter data assimilation of the Japan Sea circulation. Deep-Sea Res. (Part II), 52, 1443–1463.CrossRefGoogle Scholar
  19. Ji, M., A. Leetmaa, and J. Derber, 1995: An ocean analysis system for seasonal to inter-annual climate studies. Mon. Wea. Rev., 123, 460–481.CrossRefGoogle Scholar
  20. Keppenne, C. L., and M. M. Rienecker, 2003: Assimilation of temperature into an isopycnal ocean general circulation model using a parallel ensemble Kalman filter. J. Mar. Syst., 40–41, 363–380.CrossRefGoogle Scholar
  21. Lagerloef, G., and T. Delcroix, 2001: Sea surface salinity: A regional case study for the tropical Pacific. Observing the Ocean in the 21st Century, C. Koblinski and N. Smith, Australian Bureau of Meteorology, Melbourne, Australia, 137–148.Google Scholar
  22. Le Traon, P. Y., F. Nadal, and N. Ducet, 1998: An improved mapping method of multi-satellite altimeter data. J. Atmos. Oceanic Technol., 15, 522–534.CrossRefGoogle Scholar
  23. Levitus, S., and Coauthors, 1998: World Ocean Database 1998a, Volume 1: Introduction. NOAA Atlas NESDIS 18., U. S. Government Printing Office, Wash., D. C., 346pp.Google Scholar
  24. Maes, C., 1999: A note on the vertical scales of temperature and salinity and their signature in dynamic height in the western Pacific Ocean: Implications for data assimilation. J. Geophys. Res., 104, 15,575–15,585.Google Scholar
  25. Maes, C., 2000: Salinity variability in the equatorial Pacific Ocean during the 1993–98 period. Geophys. Res. Lett., 27, 1659–1662.CrossRefGoogle Scholar
  26. Maes, C., and D. Behringer, 2000: Using satellite-derived sea level and temperature profiles for determining the salinity variability: A new approach. J. Geophys. Res., 105(C4), 8537–8547.CrossRefGoogle Scholar
  27. Maes, C., D. Behringer, R. W. Reynolds, and M. Ji, 2000: Retrospective analysis of the salinity variability in the western tropical Pacific Ocean using an indirect minimization approach. J. Atmos. Oceanic Technol., 17, 512–524.CrossRefGoogle Scholar
  28. Pacanowski, R., and S. G. H. Philander, 1981: Parameterization of vertical mixing in numerical models of the tropical ocean. J. Phys. Oceanogr., 11, 1443–1451.CrossRefGoogle Scholar
  29. Parent, L., C.-E. Testut, J.-M. Brankart, J. Verron, P. Brasseur, and L. Gourdeau, 2003: Comparative assimilation of Topex/Poseidon and ERS alitmeter data and of TAO temperature data in the tropical Pacific ocean during 1994–1998, and the mean sea-surface height issue. J. Mar. Syst., 40–41, 381–401.CrossRefGoogle Scholar
  30. Rasmusson, E. M., and T. H. Carpenter, 1982: Variations in tropical sea surface temperature and surface wind fields associated with the Southern Oscillation/El Nino. Mon. Wea. Rev., 110, 354–384.CrossRefGoogle Scholar
  31. Reynolds, R. W., N. A. Rayner, T. M. Smith, D. C. Stokes, and W. Wang, 2002: An improved in-situ and satelltite SST analysis for climate. J. Climate, 15, 1609–1625.CrossRefGoogle Scholar
  32. Ricci, S., A. T. Weaver, J. Vialard, and P. Rogel, 2005: Incorporating state-dependent temperature-salinity constraints in the background error covariance of variational ocean data assimilation. Mon. Wea. Rev., 133, 317–338.CrossRefGoogle Scholar
  33. Roemmich, D., and Coauthors, 2001: Argo: The global array of profiling floats. Observing the Oceans in the 21st Century, C. J. Koblinsky and N. R. Smith, Eds., GODAE Project Office, Bureau of Meteorology, Australia, 248–257.Google Scholar
  34. Rogel, P., A. T. Weaver, N. Daget, S. Ricci, and E. Machu, 2005: Ensembles of global ocean analyses for seasonal climate prediction: Impact of temperature assimilation. Tellus, 57A, 375–386.Google Scholar
  35. Smith, N. R., and G. Meyers, 1996: An evaluation of expendable bathythermograph and Tropical Atmosphere-Ocean Array for monitoring tropical ocean variability. J. Geophys. Res., 101(C12), 28 489–28 501.CrossRefGoogle Scholar
  36. Troccoli, A., and Coauthors, 2002: Salinity adjustments in the presence of temperature data assimilation. Mon. Wea. Rev., 130, 89–102.CrossRefGoogle Scholar
  37. Troccoli, A., and K. Haines, 1999: Use of the Temperature-Salinity relation in a data assimilation context. J. Atmos. Oceanic Technol., 16, 2011–2025.CrossRefGoogle Scholar
  38. Vialard, J., A. T. Weaver, D. L. T. Anderson, and P. Delecluse, 2003: Three-and four-dimensional variational assimilation with a general circulation model of the tropical Pacific Ocean. Part II: Physical validation. Mon. Wea. Rev., 131, 1379–1395.CrossRefGoogle Scholar
  39. Vossepoel, F., and D. W. Behringer, 2000: Impact of sea level assimilation on salinity variability in the western equatorial Pacific. J. Phys. Oceanogr., 30, 1706–1721.CrossRefGoogle Scholar
  40. Vossepoel, F. C., R. W. Reynolds, and L. Miller, 1999: Use of sea level observations to estimate salinity variability in the tropical Pacific. J. Atmos. Oceanic Technol., 16, 1401–1415.CrossRefGoogle Scholar
  41. Weaver, A. T., J. Vialard, and D. L. T. Anderson, 2003: Three-and four-dimensional variational assimilation with a general circulation model of the tropical Pacific Ocean. Part I: Formulation, internal diagnostics, and consistency checks. Mon. Wea. Rev., 131, 1360–1378.CrossRefGoogle Scholar
  42. Yan, Changxiang, J. Zhu, R. Li, and G. Zhou, 2004: Roles of vertical correlations of background error and T-S relations in estimation of temperature and salinity profiles from sea surface dynamic height. J. Geophys. Res., 109, C08010, doi:10.1029/2003JC002224.Google Scholar
  43. Zhang, R., and M. Endoh, 1992: A free surface general circulation model for the tropical Pacific Ocean. J. Geophys. Res., 97(C7), 11237–11255.CrossRefGoogle Scholar
  44. Zhou Guangqing, and Li Xu, 2000: An oceanic data assimilation system based on a global OGCM, Corpus for Pre-processing System for Data Input of Climate Models. Documents for National Key Project-Studies on Short-Term Climate Prediction System in China (1996–2000), Sub-project 2–6 (96-908-02-06), 1, 34–43.Google Scholar
  45. Zhu Jiang and Yan Changxiang, 2006: Nonlinear balance constraints in 3DVAR data assimilation. Science in China (D), 49(3), 331–336.Google Scholar
  46. Zhu Jiang, Zhou Guangqing, Yan Changxiang, Fu Weiwei, and You Xiaobao, 2006: A three-dimensional variational ocean data assimilation system: Scheme and preliminary results. Science in China (D), 49(11), 1212–1222.Google Scholar

Copyright information

© Science Press 2007

Authors and Affiliations

  • Yan Changxiang  (闫长香)
    • 1
  • Zhu Jiang  (朱江)
    • 1
  • Zhou Guangqing  (周广庆)
    • 2
  1. 1.International Center for Climate and Environment Sciences, Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina
  2. 2.Information Science Center, Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina

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