Abstract
Isopycnal analyses were performed on the Global Ocean Data Assimilation System (GODAS) to determine the oceanic processes leading to so-called second-year cooling of the La Niña event. In 2010–12, a horseshoe-like pattern was seen, connecting negative temperature anomalies off and on the Equator, with a dominant influence from the South Pacific. During the 2010 La Niña event, warm waters piled up at subsurface depths in the western tropical Pacific. Beginning in early 2011, these warm subsurface anomalies propagated along the Equator toward the eastern basin, acting to reverse the sign of sea surface temperature (SST) anomalies (SSTAs) there and initiate a warm SSTA. However, throughout early 2011, pronounced negative anomalies persisted off the Equator in the subsurface depths of the South Pacific. As isopycnal surfaces outcropped in the central equatorial Pacific, negative anomalies from the subsurface spread upward along with mean circulation pathways, naturally initializing a cold SSTA. In the summer, a cold SSTA reappeared in the central basin, which subsequently strengthened due to the off-equatorial effects mostly in the South Pacific. These SSTAs acted to initiate local coupled air-sea interactions, generating atmospheric-oceanic anomalies that developed and evolved with the second-year cooling in the fall of 2011. However, the cooling tendency in mid-2012 did not develop into another La Niña event, since the cold anomalies in the South Pacific were not strong enough. An analysis of the 2007–09 La Niña event revealed similar processes to the 2010–12 La Niña event.
Similar content being viewed by others
References
Battisti, D. S., and A. C. Hirst, 1989: Interannual variability in the tropical atmosphere-ocean system: Influence of the basis state, ocean geometry and nonlinearity. J. Atmos. Sci., 46, 1687–1712.
Behringer, D. W., and Y. Xue, 2004: Evaluation of the global ocean data assimilation system at NCEP: The Pacific Ocean. Preprints, Eighth Symp. on Integrated Observing and Assimilation Systems for Atmosphere, Oceans, and Land Surface, Seattle, WA, Amer. Meteor. Soc., 2. 3. [Available online at https://ams.confex.com/ams/84Annual/techprogram/paper_70720.htm.]
Cane, M. A., and S. E. Zebiak, 1985: A theory for El Niño and the Southern Oscillation. Science, 228, 1085–1087.
Chang, P., B. S. Giese, L. Ji, H. F. Seidel, and F. Wang, 2001: Decadal change in the South Tropical Pacific in a global assimilation analysis. Geophys. Res. Lett., 28, 3461–3464.
Choi, J., S. I. An., S. W. Yeh, and J. Y. Yu, 2013: ENSOlike and ENSO-induced tropical Pacific decadal variability in CGCMs. J. Climate, 26, 1485–1501.
Cox, M. D., and K. Bryan, 1984: A numerical model of the ventilated thermocline, J. Phys. Oceanogr., 14, 674–687.
Hu, Z. -Z., A. Kumar, Y. Xue, and B. Jha, 2014: Why were some La Niña followed by another La Niña? Climate Dyn., 42, 1029–1042, doi: 10.1007/s00382-013-1917-3.
Jin, F. -F., 1997: An equatorial ocean recharge paradigm for ENSO. Part I: Conceptual model. J. Atmos. Sci., 54, 811–829.
Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Meteor. Soc., 77(3), 437–471.
Luo, J.-J., S. Masson, S. K. Behera, P. Delecluse, S. Gualdi, A. Navarra, and T. Yamagata, 2003: South Pacific Origin of the decadal ENSO-like variation as simulated by a coupled GCM. Geophys. Res. Lett., 30(24), 2250, doi: 10.1029/2003GL018649.
Luo, Y. -Y., L. M. Rothstein, R.-H. Zhang, and A. J. Busalacchi, 2005: On the connection between South Pacific subtropical spiciness anomalies and decadal equatorial variability in an ocean general circulation model. J. Geophys. Res., 110, C10002, doi: 10.1029/2004JC002655.
McCreary, J. P. Jr., and D. L. T. Anderson, 1984: A simple model of El Niño and the Southern Oscillation. Mon. Wea. Rev., 112, 934–946.
Philander, S. G. H, 1992: Ocean-atmosphere interactions in the tropics: A review of recent theories and models. J. Appl. Meteoro., 31, 938–945.
Wang, X., C. Y. Li, and W. Zhou, 2007: Interdecadal mode and its propagating characteristics of SSTA in the South Pacific. Meteor. Atmos. Phys., 98, 115–124, doi: 10.1007/s00703-006-0235-2.
Wang, X., C. Z. Wang, W. Zhou, D. X. Wang, and J. Song, 2011: Teleconnected influence of North Atlantic sea surface temperature on the El Niño onset. Climate Dyn., 37, 663–676, doi: 10.1007/s00382-010-0833-z.
Wang, X., C. Z. Wang, W. Zhou, L. Liu, and D. X. Wang, 2013: Remote influence of North Atlantic SST on the equatorial westerly wind anomalies in the western Pacific for initiating an El Niño event: An Atmospheric General Circulation Model Study. Atmos. Sci. Lett., 14, 107–111.
Yu, Z.-J., P. S. Schopf, and J. P. McCreary Jr., 1997: On the annual cycle of upper-ocean circulation in the eastern equatorial Pacific. J. Phys. Oceanogr., 27 309–324.
Zebiak, S. E., and M. A. Cane, 1987: A model El Niño-Southern Oscillation. Mon. Wea. Rev., 115, 2262–2278.
Zhang, R.-H., and A. J. Busalacchi, 1999: A possible link between off-equatorial warm anomalies propagating along the NECC path and the onset of the 1997–98 El Niño. Geophys. Res. Lett., 26(18), 2873–2876.
Zhang, R. -H., and L. M. Rothstein, 2000: Role of off-equatorial subsurface anomalies in initiating the 1991–1992 El Niño as revealed by the National Centers for Environmental Prediction ocean reanalysis data. J. Geophys. Res., 105(C3), 6327–6339.
Zhang, R.-H., L. M. Rothstein, A. J. Busalacchi, and X. Z. Liang, 1999: The onset of the 1991–92 El Niño event in the tropical Pacific Ocean: The NECC subsurface pathway. Geophys. Res. Lett., 26(7), 847–850.
Zhang, R.-H., S. E. Zebiak, R. Kleeman, and N. Keenlyside, 2003: A new intermediate coupled model for El Niño simulation and prediction. Geophys. Res. Lett., 30(19), doi: 10.1029/2003GL018010.
Zhang, R. -H., S. E. Zebiak, R. Kleeman, and N. Keenlyside, 2005: Retrospective El Nino forecast using an improved intermediate coupled model. Mon. Wea. Rev., 133, 2777–2802.
Zhang, R. -H., F. Zheng, J. Zhu, and Z. G. Wang, 2013: A successful real-time forecast of the 2010–11 La Niña event. Sci. Rep., 3, 1108, doi: 10.1038/srep01108.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Feng, L., Zhang, RH., Wang, Z. et al. Processes leading to second-year cooling of the 2010–12 La Niña event, diagnosed using GODAS. Adv. Atmos. Sci. 32, 424–438 (2015). https://doi.org/10.1007/s00376-014-4012-8
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00376-014-4012-8