Nonlinearity modulating intensities and spatial structures of central Pacific and eastern Pacific El Niño events
This paper compares data from linearized and nonlinear Zebiak–Cane model, as constrained by observed sea surface temperature anomaly (SSTA), in simulating central Pacific (CP) and eastern Pacific (EP) El Ni˜no. The difference between the temperature advections (determined by subtracting those of the linearized model from those of the nonlinear model), referred to here as the nonlinearly induced temperature advection change (NTA), is analyzed. The results demonstrate that the NTA records warming in the central equatorial Pacific during CP El Ni˜no and makes fewer contributions to the structural distinctions of the CP El Ni˜no, whereas it records warming in the eastern equatorial Pacific during EP El Ni˜no, and thus significantly promotes EP El Ni˜no during El Ni˜no–type selection. The NTA for CP and EP El Ni˜no varies in its amplitude, and is smaller in CP El Ni˜no than it is in EP El Ni˜no. These results demonstrate that CP El Ni˜no are weakly modulated by small intensities of NTA, and may be controlled by weak nonlinearity; whereas, EP El Ni˜no are significantly enhanced by large amplitudes of NTA, and are therefore likely to be modulated by relatively strong nonlinearity. These data could explain why CP El Ni˜no are weaker than EP El Ni˜no. Because the NTA for CP and EP El Ni˜no differs in spatial structures and intensities, as well as their roles within different El Ni˜no modes, the diversity of El Ni˜no may be closely related to changes in the nonlinear characteristics of the tropical Pacific.
Key wordsEl Niño diversity nonlinearity intensity spatial structures nonlinear temperature advection
Unable to display preview. Download preview PDF.
- Ashok, K., S. K. Behera, S. A. Rao, H. Y. Weng, and T. Yamagata, 2007: El Niño Modoki and its possible teleconnection. J. Geophys. Res., 112, doi: 10.1029/2006JC003798.Google Scholar
- Duan, W. S., and M. Mu, 2006: Investigating decadal variability of El Niño–Southern Oscillation asymmetry by conditional nonlinear optimal perturbation. J. Geophys. Res., 111, doi: 10.1029/2005JC003458.Google Scholar
- Duan, W. S., M. Mu, and B. Wang, 2004: Conditional nonlinear optimal perturbations as the optimal precursors for El Niño-Southern Oscillation events. J. Geophys. Res., 109, doi: 10.1029/2004JD004756.Google Scholar
- Duan, W. S., H. Xu, and M. Mu, 2008: Decisive role of nonlinear temperature advection in El Niño and La Niña amplitude asymmetry. J. Geophys. Res., 113, doi: 10.1029/2006JC 003974.Google Scholar
- Feng, J., and J. P. Li, 2011: Influence of El Niño Modoki on spring rainfall over South China. J. Geophys. Res., 116, doi: 10.1029/2010JD015160.Google Scholar
- Guan, C., and M. J. McPhaden, 2016: Ocean processes affecting the twenty-first-century shift in ENSO SST variability. J. Climate, 29, doi: 10.1175/JCLI-D-15-0870. 1.Google Scholar
- Jin, F.-F., 1997a: An equatorial ocean recharge paradigm for ENSO. Part I: Conceptual model. J. Atmos. Sci., 54, 811–829.Google Scholar
- Jin, F.-F., 1997b: An equatorial ocean recharge paradigm for ENSO. Part II: A stripped-down coupled model. J. Atmos. Sci., 54, 830–847.Google Scholar
- Lee, T., and M. J. McPhaden, 2010: Increasing intensity of El Niño in the central-equatorial Pacific. Geophys. Res. Lett., 37, doi: 10.1029/2010GL044007.Google Scholar
- Li, J. P., and Coauthors, 2013: Progress in air–land–sea interactions in Asia and their role in global and Asian climate change. Chinese Journal of Atmospheric Sciences, 37(2), 518–538. (in Chinese)Google Scholar
- Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res., 108, 4407, doi: 10.1029/2002JD002670.CrossRefGoogle Scholar
- Wang, C. Z., and J. Picaut, 2004: Understanding ENSO physics— A review. Earth’s Climate: The Ocean-Atmosphere Interaction, C. Wang, S. P. Xie and J. A. Carton, Eds., American Geophysical Union, 21–48.Google Scholar