Ocean Dynamics

, Volume 65, Issue 5, pp 691–705 | Cite as

Interannually varying salinity effects on ENSO in the tropical pacific: a diagnostic analysis from Argo

Article

Abstract

In this paper, three-dimensional temperature and salinity fields from Argo profiles are used to diagnose the interannual variations of some related upper oceanic fields in the tropical Pacific, with a focus on interannually varying salinity effects on the El Niño-Southern Oscillation (ENSO) events. It is clearly demonstrated that the salinity field plays a significantly large role in modulating the density and mixed layer (ML) over the western-central tropical Pacific. In particular, the contribution of interannually varying salinity to the interannual variations in density, ML, and stratification is surprisingly larger than that of interannually varying temperature. Over the entire region west of the dateline, the salinity effects are not limited to the surface but are clearly seen below the ML as represented in density and stratification fields. Furthermore, the mechanism for how the anomalous salinity field is modulating the ENSO cycle is investigated and explained through the El Niño (2009–2010) and La Niña (2010–2011) cases. Evidently, salinity field is shown to exert a significant influence on interannual variability as it directly affects the vertical mixing and entrainment at the base of the ML, the processes important to sea surface temperature (SST) in the equatorial regions.

Keywords

Salinity effect ENSO Argo Western-central tropical Pacific 

Notes

Acknowledgments

This work was supported by the National Program for Support of Top-notch Young Professionals, the National Basic Research Program of China (Grant Nos. 2012CB417404 and 2012CB956000), the Chinese Academy Sciences’ Project “Western Pacific Ocean System: Structure, Dynamics and Consequences” (WPOS; Grant Nos. XDA10010405 and XDA11010301), and the National Natural Science Foundation of China (Grant Nos. 41176014 and 41475101).

References

  1. Adler RF, Huffman GJ, Chang A, Ferraro R, Xie P, Janowiak J, Rudolf B, Schneider U, Curtis S, Bolvin D, Gruber A, Susskind J, Arkin P, Nelkin E (2003) The version-2 global precipitation and climatology project (GPCP) monthly precipitation analysis (1979–present). J Hydrometeorol 4:1147–1167CrossRefGoogle Scholar
  2. Ashok K, Yamagata T (2009) Climate change: the El Niño with a difference. Nature 461:481–484CrossRefGoogle Scholar
  3. Bjerknes J (1969) Atmospheric teleconnections from the equatorial Pacific. Mon Weather Rev 97:163–172CrossRefGoogle Scholar
  4. Bosc C, Delcroix T, Maes C (2009) Barrier layer variability in the western Pacific warm pool from 2000 to 2007. J Geophys Res 114, C06023. doi: 10.1029/2008JC005187 Google Scholar
  5. Cravatte S, Delcroix T, Zhang D, McPhaden M, Leloup J (2009) Observed freshening and warming of the western Pacific warm pool. Clim Dyn 33:565–589. doi: 10.1017/s00382-009-0526-7 CrossRefGoogle Scholar
  6. de Boyer Montégut C, Madec G, Fischer AS, Lazar A, Ludicone D (2004) Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J Geophys Res 109, C12003. doi: 10.1029/2004JC002378 CrossRefGoogle Scholar
  7. Delcroix T (1998) Observed surface oceanic and atmospheric variability in the tropical Pacific at seasonal and ENSO timescales: a tentative overview. J Geophys Res 103(C9):18611–18633CrossRefGoogle Scholar
  8. Delcroix T, Henin C (1991) Seasonal and interannual variations of sea surface salinity in the tropical Pacific ocean. J Geophys Res 96:22135–22150CrossRefGoogle Scholar
  9. Delcroix T, Cravatte S, McPhaden MJ (2007) Decadal variations and trends in tropical Pacific sea surface salinity since 1970. J Geophys Res 112, C03012. doi: 10.1029/2006JC003801 Google Scholar
  10. Eldin G, Rodier M, Radenac M-H (1997) Physical and nutrient variability in the upper equatorial Pacific associated with westerly wind forcing and wave activity in October 1994. Deep-Sea Res II 44:1783–1800CrossRefGoogle Scholar
  11. Fedorov AV, Pacanowski RC, Philander SGH, Boccaletti G (2004) The effect of salinity on the wind-driven circulation and the thermal structure of the upper ocean. J Phys Oceanogr 34:1949–1966CrossRefGoogle Scholar
  12. Gill AE (1982) Atmosphere–ocean dynamics. Academic, New York, 662 ppGoogle Scholar
  13. Hackert E, Ballabrera-Poy J, Busalacchi AJ, Zhang R-H, Murtugudde R (2011) Impact of sea surface salinity assimilation on coupled forecasts in the tropical Pacific. J Geophys Res 116, C05009. doi: 10.1029/2010JC006708 Google Scholar
  14. Hosoda S, Ohira T, Nakamura T (2008) A monthly mean dataset of global oceanic temperature and salinity derived from Argo float observations. JAMSTEC Rep Res Dev 8:47–59CrossRefGoogle Scholar
  15. Huang B, Mehta VM (2005) Response of the Pacific and Atlantic oceans to interannual variations in net atmospheric freshwater. J Geophys Res 110, C08008. doi: 10.1029/2004JC002830 Google Scholar
  16. Kanamitsu M, Ebisuzaki W, Woollen J, Yang S, Hnilo JJ, Fiorino M, Potter GL (2002) NCEP-DEO AMIP-II reanalysis (R-2). Bull Am Meteorol Soc 83:1631–1643. doi: 10.1175/BAMS-83-11-1631 CrossRefGoogle Scholar
  17. Kim SB, Lee T, Fukumori I (2007) Mechanisms controlling the interannual variation of mixed layer temperature averaged over the Niño-3 region. J Clim 20:3822–3843CrossRefGoogle Scholar
  18. Lagerloef GSE (2002) Introduction to the special section: the role of surface salinity on upper ocean dynamics, air-sea interaction and climate. J Geophys Res 107:8000. doi: 10.1029/2002JC001669 CrossRefGoogle Scholar
  19. Lee T, McPhaden MJ (2010) Increasing intensity of El Niño in the central-equatorial Pacific. Geophys Res Lett 37, L14603. doi: 10.1029/2010GL044007 Google Scholar
  20. Lukas R, Lindstrom E (1991) The mixed layer of the western equatorial Pacific Ocean. J Geophys Res 96:3343–3357CrossRefGoogle Scholar
  21. Maes C (2000) Salinity variability in the equatorial Pacific Ocean during the 1993–98 period. Geophys Res Lett 27:1659–1662. doi: 10.1029/1999GL011261 CrossRefGoogle Scholar
  22. Maes C (2008) On the ocean salinity stratification observed at the eastern edge of the equatorial pacific warm pool. J Geophys Res 113, C03027. doi: 10.1029/2007JC004297 Google Scholar
  23. Maes C, McPhaden MJ, Behringer D (2002) Signatures of salinity variability in tropical Pacific Ocean dynamic height anomalies. J Geophys Res 107(C12):8012. doi: 10.1029/2000JC000737 CrossRefGoogle Scholar
  24. Maes C, Picaut J, Belamari S (2005) Importance of salinity barrier layer for the buildup of El Niño. J Clim 18:104–118. doi: 10.1175/JCLI-3214.1 CrossRefGoogle Scholar
  25. Maes C, Ando K, Delcroix T, Kessler WS, McPhaden MJ, Roemmich D (2006) Observed correlation of surface salinity, temperature and barrier layer at the eastern edge of the western Pacific warm pool. Geophys Res Lett 33, L06601. doi: 10.1029/2005GL024772 Google Scholar
  26. McPhaden MJ (2004) Evolution of the 2002/03 El Niño. Bull Am Meteorol Soc 85:677–695CrossRefGoogle Scholar
  27. McPhaden MJ, Yu X (1999) Equatorial waves and the 1997–98 El Niño. Geophys Res Lett 26:2961–2964CrossRefGoogle Scholar
  28. Meehl GA, Gent PR, Arblaster JM, Otto-Bliesner B, Brady E, Craig AP (2001) Factors that affect the amplitude of El Niño in global coupled climate models. Clim Dyn 17:515–526CrossRefGoogle Scholar
  29. Miller JR (1976) The salinity effect in a mixed-layer ocean model. J Phys Oceanogr 6:29–35CrossRefGoogle Scholar
  30. Moore AM, Kleeman R (1999) The nonnormal nature of El Niño and intraseasonal variability. J Clim 12:2965–2982CrossRefGoogle Scholar
  31. Murtugudde R, Busalacchi AJ (1998) Salinity effects in a tropical ocean model. J Geophys Res 103:3283–3300CrossRefGoogle Scholar
  32. Picaut J, Ioualalen M, Menkes C, Delcroix T, McPhaden MJ (1996) Mechanism of the zonal displacements of the Pacific warm pool: implications for ENSO. Science 274:1486–1489. doi: 10.1126/science.274.5292.1486 CrossRefGoogle Scholar
  33. Qu T, Yu J-Y (2014) ENSO indices from sea surface salinity observed by Aquarius and Argo. J Oceanogr 70(4):367–375CrossRefGoogle Scholar
  34. Qu T, Song YT, Maes C (2014) Sea surface salinity and barrier layer variability in the equatorial Pacific as seen from Aquarius and Argo. J Geophys Res 119(1):15–29. doi: 10.1002/2013JC009375 CrossRefGoogle Scholar
  35. Sato K, Suga T, Hanawa K (2004) Barrier layer in the North Pacific subtropical gyre. Geophys Res Lett 31, L05301. doi: 10.1029/2003GL018590 Google Scholar
  36. Sato K, Suga T, Hanawa K (2006) Barrier layers in the subtropical gyres of the world’s oceans. Geophys Res Lett 33, L08603. doi: 10.1029/2005GL025631 Google Scholar
  37. Singh A, Delcroix T, Cravatte S (2011) Contrasting the flavors of El Niño-Southern Oscillation using sea surface salinity observations. J Geophys Res 116, C06016. doi: 10.1029/2010JC006862 Google Scholar
  38. Sprintall J, Tomczak M (1992) Evidence of the barrier layer in the surface layer of the tropics. J Geophys Res 97:7305–7316CrossRefGoogle Scholar
  39. Xie S-P, Deser C, Vecchi GA, Ma J, Teng H, Wittenberg AT (2010) Global warming pattern formation: sea surface temperature and rainfall. J Clim 23:966–986CrossRefGoogle Scholar
  40. Yeh S-W, Kug J-S, Dewitte B, Kwon M-H, Kirtman B, Jin F-F (2009) El Niño in a changing climate. Nature 461:511–514CrossRefGoogle Scholar
  41. Yu B, Boer GJ (2002) The roles of radiation and dynamic processes in the El Niño-like response to global warming. Clim Dyn 19:539–553CrossRefGoogle Scholar
  42. Yu J-Y, Kao H-Y (2007) Decadal changes of ENSO persistence barrier in SST and ocean heat content indices: 1958–2001. J Geophys Res 112, D13106. doi: 10.1029/2006JD007654 Google Scholar
  43. Yu L, Weller RA (2007) Objectively analyzed air-sea heat fluxes for the global ice-free oceans (1981–2005). Bull Am Meteorol Soc 88:527–539CrossRefGoogle Scholar
  44. Yu J-Y, Zou Y, Kim ST, Lee T (2012) The changing impact of El Niño on US winter temperatures. Geophys Res Lett 39, L15702. doi: 10.1029/2012GL052483 Google Scholar
  45. Zebiak SE, Cane MA (1987) A model El Niño/Southern Oscillation. Mon Weather Rev 115:2262–2278CrossRefGoogle Scholar
  46. Zhang R-H, Busalacchi AJ (2009) Freshwater flux (FWF)-induced oceanic feedback in a hybrid coupled model of the tropical Pacific. J Clim 22:853–879CrossRefGoogle Scholar
  47. Zhang R-H, Levitus S (1997) Interannual variability of the coupled Tropical Pacific ocean–atmosphere system associated with the El Niño/Southern Oscillation. J Clim 10:1312–1330CrossRefGoogle Scholar
  48. Zhang R-H, Zebiak SE (2004) An embedding method for improving interannual variability simulations in a hybrid coupled model of the tropical Pacific ocean–atmosphere system. J Clim 17(14):2794–2812CrossRefGoogle Scholar
  49. Zhang R-H, Wang G-H, Chen D, Busalacchi AJ, Hackert EC (2010) Interannual biases induced by freshwater flux and coupled feedback in the tropical Pacific. Mon Weather Rev 138:1715–1737CrossRefGoogle Scholar
  50. Zhang R-H, Zheng F, Zhu JS, Pei YH, Zheng QA, Wang ZG (2012) Modulations of El Niño-Southern oscillation by climate feedbacks associated with freshwater flux and ocean biology in the tropical pacific. Adv Atmos Sci 29(4):647–660CrossRefGoogle Scholar
  51. Zheng F, Zhang R-H (2012) Effects of interannual salinity variability and freshwater flux forcing on the development of the 2007/08 La Niña event diagnosed from Argo and satellite data. Dyn Atmos Oceans 57:45–57. doi: 10.1016/j.dynatmoce.2012.06.002 CrossRefGoogle Scholar
  52. Zheng F, Zhu J (2008) Balanced multivariate model errors of an intermediate coupled model for ensemble Kalman filter data assimilation. J Geophys Res 113, C07002. doi: 10.1029/2007JC004621 Google Scholar
  53. Zheng F, Zhu J (2010) Coupled assimilation for an intermediated coupled ENSO prediction model. Ocean Dyn 60:1061–1073. doi: 10.1007/s10236-010-0307-1 CrossRefGoogle Scholar
  54. Zheng F, Zhang R-H, Zhu J (2014a) Effects of interannual salinity variability on the barrier layer in the western-central equatorial Pacific: a diagnostic analysis from Argo. Adv Atmos Sci 31(3):532–542. doi: 10.1007/s00376-013-3061-8 CrossRefGoogle Scholar
  55. Zheng F, Fang X-H, Yu J-Y, Zhu J (2014b) Asymmetry of the Bjerknes positive feedback between the two types of El Niño. Geophys Res Lett 41:7651–7657. doi: 10.1002/2014GL062125 CrossRefGoogle Scholar
  56. Zhu J-S, Huang B-H, Zhang R-H, Hu Z-Z, Kumar A, Balmaseda MA, Kinter JL III (2014) Salinity anomaly as a trigger for ENSO events. Sci Rep 4:6821. doi: 10.1038/srep06821 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  1. 1.International Center for Climate and Environment Science (ICCES), Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina
  2. 2.Key Laboratory of Ocean Circulation and Waves, Institute of OceanologyChinese Academy of SciencesQingdaoChina

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