• Alexander, M. A., I. Bladé, M. Newman, J. R. Lanzante, N.-C. Lau, and J. D. Scott, 2002: The atmospheric bridge: The influence of ENSO teleconnections on air–sea interaction over the global oceans. J. Climate, 15, 22052231, https://doi.org/10.1175/1520-0442(2002)015<2205:TABTIO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Alexander, M. A., D. J. Vimont, P. Chang, and J. D. Scott, 2010: The impact of extratropical atmospheric variability on ENSO: Testing the seasonal footprinting mechanism using coupled model experiments. J. Climate, 23, 28852901, https://doi.org/10.1175/2010JCLI3205.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Amaya, D. J., 2019: The Pacific meridional mode and ENSO: A review. Curr. Climate Change Rep., 5, 296307, https://doi.org/10.1007/s40641-019-00142-x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • An, S.-I., 2008: Interannual variations of the tropical ocean instability wave and ENSO. J. Climate, 21, 36803686, https://doi.org/10.1175/2008JCLI1701.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • An, S.-I., and F.-F. Jin, 2004: Nonlinearity and asymmetry of ENSO. J. Climate, 17, 23992412, https://doi.org/10.1175/1520-0442(2004)017<2399:NAAOE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Anderson, B. T., R. C. Perez, and A. Karspeck, 2013: Triggering of El Niño onset through trade wind–induced charging of the equatorial Pacific. Geophys. Res. Lett., 40, 12121216, https://doi.org/10.1002/grl.50200.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Barnett, T. P., 1983: Interaction of the monsoon and Pacific trade wind system at interannual time scales. Part I: The equatorial zone. Mon. Wea. Rev., 111, 756773, https://doi.org/10.1175/1520-0493(1983)111<0756:IOTMAP>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Battisti, D. S., and A. C. Hirst, 1989: Interannual variability in a tropical atmosphere–ocean model: Influence of the basic state, ocean geometry, and nonlinearity. J. Atmos. Sci., 46, 16871712, https://doi.org/10.1175/1520-0469(1989)046<1687:IVIATA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Baturin, N. G., and P. P. Niiler, 1997: Effects of instability waves in the mixed layer of the equatorial Pacific. J. Geophys. Res., 102, 27 77127 793, https://doi.org/10.1029/97JC02455.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Behringer, D., and Y. Xue, 2004: Evaluation of the Global Ocean Data Assimilation System at NCEP: The Pacific Ocean. Eighth Symp. on Integrated Observing and Assimilation Systems for Atmosphere, Oceans, and Land Surface, Seattle, WA, Amer. Meteor. Soc., 2.3, https://ams.confex.com/ams/pdfpapers/70720.pdf.

  • Bjerknes, J., 1969: Atmospheric teleconnections from the equatorial Pacific. Mon. Wea. Rev., 97, 163172, https://doi.org/10.1175/1520-0493(1969)097<0163:ATFTEP>2.3.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Boucharel, J., and F.-F. Jin, 2020: A simple theory for the modulation of tropical instability waves by ENSO and the annual cycle. Tellus, 72, 114, https://doi.org/10.1080/16000870.2019.1700087.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Boucharel, J., A. Timmermann, and F.-F. Jin, 2013: Zonal phase propagation of ENSO sea surface temperature anomalies: Revisited. Geophys. Res. Lett., 40, 40484053, https://doi.org/10.1002/grl.50685.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Boucharel, J., A. Timmermann, A. Santoso, M. H. England, F.-F. Jin, and M. A. Balmaseda, 2015: A surface layer variance heat budget for ENSO. Geophys. Res. Lett., 42, 35293537, https://doi.org/10.1002/2015GL063843.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bryden, H. L., and E. C. Brady, 1989: Eddy momentum and heat fluxes and their effects on the circulation of the equatorial Pacific Ocean. J. Mar. Res., 47, 5579, https://doi.org/10.1357/002224089785076389.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cane, M. A., and S. E. Zebiak, 1985: A theory for El Niño and the Southern Oscillation. Science, 228, 10851087, https://doi.org/10.1126/science.228.4703.1085.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chakravorty, S., R. Perez, B. Anderson, B. Giese, S. Larson, and V. Pivotti, 2020: Testing the trade wind charging mechanism and its influence on ENSO variability. J. Climate, 33, 73917411, https://doi.org/10.1175/JCLI-D-19-0727.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chang, P., L. Zhang, R. Saravanan, D. J. Vimont, J. C. H. Chiang, L. Ji, H. Seidel, and M. K. Tippett, 2007: Pacific meridional mode and El Niño–Southern Oscillation. Geophys. Res. Lett., 34, L16608, https://doi.org/10.1029/2007GL030302.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, D., and et al. , 2015: Strong influence of westerly wind bursts on El Niño diversity. Nat. Geosci., 8, 339345, https://doi.org/10.1038/ngeo2399.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chiang, J. C. H., and D. J. Vimont, 2004: Analogous Pacific and Atlantic meridional modes of tropical atmosphere–ocean variability. J. Climate, 17, 41434158, https://doi.org/10.1175/JCLI4953.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Cox, M. D., 1980: Generation and propagation of 30-day waves in a numerical model of the Pacific. J. Phys. Oceanogr., 10, 11681186, https://doi.org/10.1175/1520-0485(1980)010<1168:GAPODW>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Graham, T., 2014: The importance of eddy permitting model resolution for simulation of the heat budget of tropical instability waves. Ocean Modell., 79, 2132, https://doi.org/10.1016/j.ocemod.2014.04.005.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ham, Y.-G., and I.-S. Kang, 2011: Improvement of seasonal forecasts with inclusion of tropical instability waves on initial conditions. Climate Dyn., 36, 12771290, https://doi.org/10.1007/s00382-010-0743-0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hansen, D. V., and C. A. Paul, 1984: Genesis and effects of long waves in the equatorial Pacific. J. Geophys. Res., 89, 10 43110 440, https://doi.org/10.1029/JC089iC06p10431.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Harrison, D. E., and G. A. Vecchi, 1999: On the termination of El Niño. Geophys. Res. Lett., 26, 15931596, https://doi.org/10.1029/1999GL900316.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hersbach, H., and D. Dee, 2016: ERA5 reanalysis is in production. ECMWF Newsletter, No. 147, ECMWF, Reading, United Kingdom, 7, https://www.ecmwf.int/en/newsletter/147/news/era5-reanalysis-production.

  • Holmes, R. M., and L. N. Thomas, 2016: Modulation of tropical instability wave intensity by equatorial Kelvin waves. J. Phys. Oceanogr., 46, 26232643, https://doi.org/10.1175/JPO-D-16-0064.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Holmes, R. M., S. McGregor, A. Santoso, and M. H. England, 2019: Contribution of tropical instability waves to ENSO irregularity. Climate Dyn., 52, 18371855, https://doi.org/10.1007/s00382-018-4217-0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hu, S., and A. V. Fedorov, 2016: Exceptionally strong easterly wind burst stalling El Niño of 2014. Proc. Natl. Acad. Sci. USA, 113, 20052010, https://doi.org/10.1073/pnas.1514182113.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hu, S., and A. V. Fedorov, 2019: The extreme El Niño of 2015–2016: The role of westerly and easterly wind bursts, and preconditioning by the failed 2014 event. Climate Dyn., 52, 73397357, https://doi.org/10.1007/s00382-017-3531-2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Huang, B., Y. Xue, D. Zhang, A. Kumar, and M. J. McPhaden, 2010: The NCEP GODAS ocean analysis of the tropical Pacific mixed layer heat budget on seasonal to interannual time scales. J. Climate, 23, 49014925, https://doi.org/10.1175/2010JCLI3373.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Huang, B., and et al. , 2017: Extended Reconstructed Sea Surface Temperature, version 5 (ERSSTv5): Upgrades, validations, and intercomparisons. J. Climate, 30, 81798205, https://doi.org/10.1175/JCLI-D-16-0836.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Im, S.-H., S.-I. An, M. Lengaigne, and Y. Noh, 2012: Seasonality of tropical instability waves and its feedback to the seasonal cycle in the tropical eastern Pacific. Sci. World J., 2012, 111, https://doi.org/10.1100/2012/612048.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Imada, Y., and M. Kimoto, 2012: Parameterization of tropical instability waves and examination of their impact on ENSO characteristics. J. Climate, 25, 45684581, https://doi.org/10.1175/JCLI-D-11-00233.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jin, F.-F., 1997a: An equatorial ocean recharge paradigm for ENSO. Part I: Conceptual model. J. Atmos. Sci., 54, 811829, https://doi.org/10.1175/1520-0469(1997)054<0811:AEORPF>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jin, F.-F., 1997b: An equatorial ocean recharge paradigm for ENSO. Part II: A stripped-down coupled model. J. Atmos. Sci., 54, 830847, https://doi.org/10.1175/1520-0469(1997)054<0830:AEORPF>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jin, F.-F., S.-I. An, A. Timmermann, and J. Zhao, 2003: Strong El Niño events and nonlinear dynamical heating. Geophys. Res. Lett., 30, 1120, https://doi.org/10.1029/2002GL016356.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jochum, M., and R. Murtugudde, 2006: Temperature advection by tropical instability waves. J. Phys. Oceanogr., 36, 592605, https://doi.org/10.1175/JPO2870.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jochum, M., M. F. Cronin, W. S. Kessler, and D. Shea, 2007: Observed horizontal temperature advection by tropical instability waves. Geophys. Res. Lett., 34, L09604, https://doi.org/10.1029/2007GL029416.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kakatkar, R., C. Gnanaseelan, J. S. Deepa, J. Chowdary, and A. Parekh, 2018: Role of ocean–atmosphere interactions in modulating the 2016 La Niña like pattern over the tropical Pacific. Dyn. Atmos. Oceans, 83, 100110, https://doi.org/10.1016/j.dynatmoce.2018.07.003.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Latif, M., and et al. , 2001: ENSIP: The El Niño Simulation Intercomparison Project. Climate Dyn., 18, 255276, https://doi.org/10.1007/s003820100174.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Legeckis, R., 1977: Long waves in the eastern equatorial Pacific Ocean: A view from a geostationary satellite. Science, 197, 11791181, https://doi.org/10.1126/science.197.4309.1179.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lengaigne, M., J.-P. Boulanger, P. Delecluse, C. Menkes, E. Guilyardi, and J. Slingo, 2004: Westerly wind events in the tropical Pacific and their influence on the coupled ocean–atmosphere system: A review. Earth’s Climate: The Ocean–Atmosphere Interaction, Geophys. Monogr., Vol. 147, Amer. Geophys. Union, 49–69, https://doi.org/10.1029/147GM03.

    • Crossref
    • Export Citation
  • Levine, A. F. Z., and M. J. McPhaden, 2016: How the July 2014 easterly wind burst gave the 2015–2016 El Niño a head start. Geophys. Res. Lett., 43, 65036510, https://doi.org/10.1002/2016GL069204.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • L’Heureux, M. L., and et al. , 2017: Observing and predicting the 2015/16 El Niño. Bull. Amer. Meteor. Soc., 98, 13631382, https://doi.org/10.1175/BAMS-D-16-0009.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, X., Z.-Z. Hu, and B. Huang, 2019: Contributions of atmosphere–ocean interaction and low-frequency variation to intensity of strong El Niño events since 1979. J. Climate, 32, 13811394, https://doi.org/10.1175/JCLI-D-18-0209.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lim, E.-P., and H. H. Hendon, 2017: Causes and predictability of the negative Indian Ocean dipole and its impact on La Niña during 2016. Sci. Rep., 7, 12619, https://doi.org/10.1038/s41598-017-12674-z.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lim, Y.-K., R. M. Kovach, S. Pawson, and G. Vernieres, 2017: The 2015/16 El Niño event in context of the MERRA-2 reanalysis: A comparison of the tropical Pacific with 1982/83 and 1997/98. J. Climate, 30, 48194842, https://doi.org/10.1175/JCLI-D-16-0800.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lyman, J. M., G. C. Johnson, and W. S. Kessler, 2007: Distinct 17- and 33-day tropical instability waves in subsurface observations. J. Phys. Oceanogr., 37, 855872, https://doi.org/10.1175/JPO3023.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Masina, S., and S. G. H. Philander, 1999: An analysis of tropical instability waves in a numerical model of the Pacific Ocean: 1. Spatial variability of the waves. J. Geophys. Res., 104, 29 61329 635, https://doi.org/10.1029/1999JC900227.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Masina, S., S. G. H. Philander, and A. B. G. Bush, 1999: An analysis of tropical instability waves in a numerical model of the Pacific Ocean: 2. Generation and energetics of the waves. J. Geophys. Res., 104, 29 63729 661, https://doi.org/10.1029/1999JC900226.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McGregor, S., N. Ramesh, P. Spence, M. H. England, M. J. McPhaden, and A. Santoso, 2013: Meridional movement of wind anomalies during ENSO events and their role in event termination. Geophys. Res. Lett., 40, 749754, https://doi.org/10.1002/grl.50136.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • McPhaden, M. J., S. E. Zebiak, and M. H. Glantz, 2006: ENSO as an integrating concept in Earth science. Science, 314, 17401745, https://doi.org/10.1126/science.1132588.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Meinen, C. S., and M. J. McPhaden, 2000: Observations of warm water volume changes in the equatorial Pacific and their relationship to El Niño and La Niña. J. Climate, 13, 35513559, https://doi.org/10.1175/1520-0442(2000)013<3551:OOWWVC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Menkes, C. E., J. G. Vialard, S. C. Kennan, J.-P. Boulanger, and G. V. Madec, 2006: A modeling study of the impact of tropical instability waves on the heat budget of the eastern equatorial Pacific. J. Phys. Oceanogr., 36, 847865, https://doi.org/10.1175/JPO2904.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Menkes, C. E., M. Lengaigne, J. Vialard, M. Puy, P. Marchesiello, S. Cravatte, and G. Cambon, 2014: About the role of westerly wind events in the possible development of an El Niño in 2014. Geophys. Res. Lett., 41, 64766483, https://doi.org/10.1002/2014GL061186.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Min, Q., J. Su, R. Zhang, and X. Rong, 2015: What hindered the El Niño pattern in 2014? Geophys. Res. Lett., 42, 67626770, https://doi.org/10.1002/2015GL064899.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Min, Q., J. Su, and R. Zhang, 2017: Impact of the South and North Pacific meridional modes on the El Niño–Southern Oscillation: Observational analysis and comparison. J. Climate, 30, 17051720, https://doi.org/10.1175/JCLI-D-16-0063.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Miyakawa, T., H. Yashiro, T. Suzuki, H. Tatebe, and M. Satoh, 2017: A Madden–Julian oscillation event remotely accelerates ocean upwelling to abruptly terminate the 1997/1998 super El Niño. Geophys. Res. Lett., 44, 94899495, https://doi.org/10.1002/2017GL074683.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • North, G. R., T. L. Bell, R. F. Cahalan, and F. J. Moeng, 1982: Sampling errors in the estimation of empirical orthogonal functions. Mon. Wea. Rev., 110, 699706, https://doi.org/10.1175/1520-0493(1982)110<0699:SEITEO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Paek, H., J.-Y. Yu, and C. Qian, 2017: Why were the 2015/2016 and 1997/1998 extreme El Niños different? Geophys. Res. Lett., 44, 18481856, https://doi.org/10.1002/2016GL071515.

    • Search Google Scholar
    • Export Citation
  • Philander, S. G. H., 1976: Instabilities of zonal equatorial currents. J. Geophys. Res., 81, 37253735, https://doi.org/10.1029/JC081i021p03725.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Picaut, J., 1997: An advective-reflective conceptual model for the oscillatory nature of the ENSO. Science, 277, 663666, https://doi.org/10.1126/science.277.5326.663.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Planton, Y., J. Vialard, E. Guilyardi, M. Lengaigne, and T. Izumo, 2018: Western Pacific oceanic heat content: A better predictor of La Niña than of El Niño. Geophys. Res. Lett., 45, 98249833, https://doi.org/10.1029/2018GL079341.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Proehl, J. A., 1996: Linear stability of equatorial zonal flows. J. Phys. Oceanogr., 26, 601621, https://doi.org/10.1175/1520-0485(1996)026<0601:LSOEZF>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Qiao, L., and R. H. Weisberg, 1995: Tropical instability wave kinematics: Observations from the tropical instability wave experiment. J. Geophys. Res., 100, 8677, https://doi.org/10.1029/95JC00305.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rasmusson, E. M., and T. H. Carpenter, 1982: Variations in tropical sea surface temperature and surface wind fields associated with the southern oscillation/El Niño. Mon. Wea. Rev., 110, 354384, https://doi.org/10.1175/1520-0493(1982)110<0354:VITSST>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reynolds, R. W., N. A. Rayner, T. M. Smith, D. C. Stokes, and W. Wang, 2002: An improved in situ and satellite SST analysis for climate. J. Climate, 15, 16091625, https://doi.org/10.1175/1520-0442(2002)015<1609:AIISAS>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ropelewski, C. F., and M. S. Halpert, 1987: Global and regional scale precipitation patterns associated with the El Niño/Southern Oscillation. Mon. Wea. Rev., 115, 16061626, https://doi.org/10.1175/1520-0493(1987)115<1606:GARSPP>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ropelewski, C. F., and M. S. Halpert, 1996: Quantifying Southern Oscillation–precipitation relationships. J. Climate, 9, 10431059, https://doi.org/10.1175/1520-0442(1996)009<1043:QSOPR>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Santoso, A., M. J. McPhaden, and W. Cai, 2017: The defining characteristics of ENSO extremes and the strong 2015/2016 El Niño. Rev. Geophys., 55, 10791129, https://doi.org/10.1002/2017RG000560.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Seiki, A., and Y. N. Takayabu, 2007: Westerly wind bursts and their relationship with intraseasonal variations and ENSO. Part I: Statistics. Mon. Wea. Rev., 135, 33253345, https://doi.org/10.1175/MWR3477.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Shinoda, T., G. N. Kiladis, and P. E. Roundy, 2009: Statistical representation of equatorial waves and tropical instability waves in the Pacific Ocean. Atmos. Res., 94, 3744, https://doi.org/10.1016/j.atmosres.2008.06.002.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Su, J., B. Xiang, B. Wang, and T. Li, 2014: Abrupt termination of the 2012 Pacific warming and its implication on ENSO prediction. Geophys. Res. Lett., 41, 90589064, https://doi.org/10.1002/2014GL062380.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Su, J., R. Zhang, X. Rong, Q. Min, and C. Zhu, 2018: Sea surface temperature in the subtropical Pacific boosted the 2015 El Niño and hindered the 2016 La Niña. J. Climate, 31, 877893, https://doi.org/10.1175/JCLI-D-17-0379.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Suarez, M. J., and P. S. Schopf, 1988: A delayed action oscillator for ENSO. J. Atmos. Sci., 45, 32833287, https://doi.org/10.1175/1520-0469(1988)045<3283:ADAOFE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Timmermann, A., and et al. , 2018: El Niño–Southern Oscillation complexity. Nature, 559, 535545, https://doi.org/10.1038/s41586-018-0252-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., and J. M. Caron, 2000: The Southern Oscillation revisited: Sea level pressures, surface temperatures, and precipitation. J. Climate, 13, 43584365, https://doi.org/10.1175/1520-0442(2000)013<4358:TSORSL>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • van Loon, H., and R. A. Madden, 1981: The Southern Oscillation. Part I: Global associations with pressure and temperature in northern winter. Mon. Wea. Rev., 109, 11501162, https://doi.org/10.1175/1520-0493(1981)109<1150:TSOPIG>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., 2006: The termination of the 1997–98 El Niño. Part II: Mechanisms of atmospheric change. J. Climate, 19, 26472664, https://doi.org/10.1175/JCLI3780.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., and D. E. Harrison, 2003: On the termination of the 2002–03 El Niño event. Geophys. Res. Lett., 30, 1964, https://doi.org/10.1029/2003GL017564.

    • Search Google Scholar
    • Export Citation
  • Vecchi, G. A., and D. E. Harrison, 2006: The termination of the 1997–98 El Niño. Part I: Mechanisms of oceanic change. J. Climate, 19, 26332646, https://doi.org/10.1175/JCLI3776.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vialard, J., C. Menkes, J.-P. Boulanger, P. Delecluse, E. Guilyardi, M. J. McPhaden, and G. Madec, 2001: A model study of oceanic mechanisms affecting equatorial Pacific sea surface temperature during the 1997–98 El Niño. J. Phys. Oceanogr., 31, 16491675, https://doi.org/10.1175/1520-0485(2001)031<1649:AMSOOM>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vimont, D. J., D. S. Battisti, and A. C. Hirst, 2001: Footprinting: A seasonal connection between the tropics and mid-latitudes. Geophys. Res. Lett., 28, 39233926, https://doi.org/10.1029/2001GL013435.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vimont, D. J., D. S. Battisti, and A. C. Hirst, 2003a: The seasonal footprinting mechanism in the CSIRO general circulation models. J. Climate, 16, 26532667, https://doi.org/10.1175/1520-0442(2003)016<2653:TSFMIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vimont, D. J., J. M. Wallace, and D. S. Battisti, 2003b: The seasonal footprinting mechanism in the Pacific: Implications for ENSO. J. Climate, 16, 26682675, https://doi.org/10.1175/1520-0442(2003)016<2668:TSFMIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wallace, J. M., E. M. Rasmusson, T. P. Mitchell, V. E. Kousky, E. S. Sarachik, and H. von Storch, 1998: On the structure and evolution of ENSO-related climate variability in the tropical Pacific: Lessons from TOGA. J. Geophys. Res., 103, 14 24114 259, https://doi.org/10.1029/97JC02905.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, M., S.-P. Xie, S. Shen, and Y. Du, 2020: Rossby and Yanai modes of tropical instability waves in the equatorial Pacific Ocean and a diagnostic model for surface currents. J. Phys. Oceanogr., 50, 30093024, https://doi.org/10.1175/JPO-D-20-0063.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, W., and M. J. McPhaden, 1999: The surface-layer heat balance in the equatorial Pacific Ocean. Part I: Mean seasonal cycle. J. Phys. Oceanogr., 29, 18121831, https://doi.org/10.1175/1520-0485(1999)029<1812:TSLHBI>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, W., and M. J. McPhaden, 2001: Surface layer temperature balance in the equatorial Pacific during the 1997–98 El Niño and 1998–99 La Niña. J. Climate, 14, 33933407, https://doi.org/10.1175/1520-0442(2001)014<3393:SLTBIT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Weisberg, R. H., and T. J. Weingartner, 1988: Instability waves in the equatorial Atlantic Ocean. J. Phys. Oceanogr., 18, 16411657, https://doi.org/10.1175/1520-0485(1988)018<1641:IWITEA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Weisberg, R. H., and C. Wang, 1997: A western Pacific oscillator paradigm for the El Niño-southern oscillation. Geophys. Res. Lett., 24, 779782, https://doi.org/10.1029/97GL00689.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wheeler, M. C., and H. H. Hendon, 2004: An all-season real-time multivariate MJO index: Development of an index for monitoring and prediction. Mon. Wea. Rev., 132, 19171932, https://doi.org/10.1175/1520-0493(2004)132<1917:AARMMI>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wilson, D., and A. Leetmaa, 1988: Acoustic Doppler current profiling in the equatorial Pacific in 1984. J. Geophys. Res., 93, 13 94713 966, https://doi.org/10.1029/JC093iC11p13947.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wu, Q., and K. P. Bowman, 2007: Interannual variations of tropical instability waves observed by the Tropical Rainfall Measuring Mission. Geophys. Res. Lett., 34, L09701, https://doi.org/10.1029/2007GL029719.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wu, Y.-K., L. Chen, C.-C. Hong, T. Li, C.-T. Chen, and L. Wang, 2018: Role of the meridional dipole of SSTA and associated cross-equatorial flow in the tropical eastern Pacific in terminating the 2014 El Niño development. Climate Dyn., 50, 16251638, https://doi.org/10.1007/s00382-017-3710-1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Xue, A., F.-F. Jin, W. Zhang, J. Boucharel, S. Zhao, and X. Yuan, 2020: Delineating the seasonally modulated nonlinear feedback onto ENSO from tropical instability waves. Geophys. Res. Lett., 47, e2019GL085863, https://doi.org/10.1029/2019GL085863.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yu, J.-Y., and W. T. Liu, 2003: A linear relationship between ENSO intensity and tropical instability wave activity in the eastern Pacific Ocean. Geophys. Res. Lett., 30, 1735, https://doi.org/10.1029/2003GL017176.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yu, Z., J. P. McCreary, and J. A. Proehl, 1995: Meridional asymmetry and energetics of tropical instability waves. J. Phys. Oceanogr., 25, 29973007, https://doi.org/10.1175/1520-0485(1995)025<2997:MAAEOT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, H., A. Clement, and P. Di Nezio, 2014a: The South Pacific meridional mode: A mechanism for ENSO-like variability. J. Climate, 27, 769783, https://doi.org/10.1175/JCLI-D-13-00082.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, H., C. Deser, A. Clement, and R. Tomas, 2014b: Equatorial signatures of the Pacific meridional modes: Dependence on mean climate state. Geophys. Res. Lett., 41, 568574, https://doi.org/10.1002/2013GL058842.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zheng, F., L. Feng, and J. Zhu, 2015: An incursion of off-equatorial subsurface cold water and its role in triggering the “double dip” La Niña event of 2011. Adv. Atmos. Sci., 32, 731742, https://doi.org/10.1007/s00376-014-4080-9.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhu, J., A. Kumar, B. Huang, M. A. Balmaseda, Z.-Z. Hu, L. Marx, and J. L. Kinter Iii, 2016: The role of off-equatorial surface temperature anomalies in the 2014 El Niño prediction. Sci. Rep., 6, 19677, https://doi.org/10.1038/srep19677.

    • Crossref
    • Search Google Scholar
    • Export Citation
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Anomalous Tropical Instability Wave Activity Hindered the Development of the 2016/17 La Niña

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  • 1 a CIC-FEMD/ILCEC, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing, China
  • | 2 b LEGOS, University of Toulouse, CNRS, IRD, CNES, UPS, Toulouse, France
  • | 3 c Department of Atmospheric Sciences, SOEST, University of Hawai‘i at Mānoa, Honolulu, Hawaii
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Abstract

Although the 1997/98 and 2015/16 El Niño events are considered to be the strongest on record, their subsequent La Niña events exhibited contrasted evolutions. In this study, we demonstrate that the extremely strong period of tropical instability waves (TIWs) at the beginning of boreal summer of 2016 played an important role in hindering the subsequent La Niña’s development by transporting extra off-equatorial heat into the Pacific cold tongue. By comparing the TIWs’ contribution based on an oceanic mixed layer heat budget analysis for the 1998 and 2016 episodes, we establish that TIW-induced nonlinear dynamical heating (NDH) is a significant contributor to the El Niño–Southern Oscillation (ENSO) phase transition in 2016. TIW-induced NDH contributed to around 0.4°C warming per month during the early boreal summer (May–June) following the 2015/16 El Niño’s peak, which is found to be an essential inhibiting factor that prevented the subsequent La Niña’s growth. A time-mean eddy kinetic energy analysis reveals that anomalous TIWs during 2016 mainly gained their energy from the baroclinic instability conversion due to a strong SST warming in the northeastern off-equatorial Pacific that promoted an increased meridional SST gradient. This highlights the importance of accurately reproducing TIW activity in ENSO simulation and the benefit of off-equatorial SST anomalies in the eastern Pacific as an independent precursor for ENSO predictions.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding authors: Dr. Wenjun Zhang, zhangwj@nuist.edu.cn; Dr. Fei-Fei Jin, jff@hawaii.edu

Abstract

Although the 1997/98 and 2015/16 El Niño events are considered to be the strongest on record, their subsequent La Niña events exhibited contrasted evolutions. In this study, we demonstrate that the extremely strong period of tropical instability waves (TIWs) at the beginning of boreal summer of 2016 played an important role in hindering the subsequent La Niña’s development by transporting extra off-equatorial heat into the Pacific cold tongue. By comparing the TIWs’ contribution based on an oceanic mixed layer heat budget analysis for the 1998 and 2016 episodes, we establish that TIW-induced nonlinear dynamical heating (NDH) is a significant contributor to the El Niño–Southern Oscillation (ENSO) phase transition in 2016. TIW-induced NDH contributed to around 0.4°C warming per month during the early boreal summer (May–June) following the 2015/16 El Niño’s peak, which is found to be an essential inhibiting factor that prevented the subsequent La Niña’s growth. A time-mean eddy kinetic energy analysis reveals that anomalous TIWs during 2016 mainly gained their energy from the baroclinic instability conversion due to a strong SST warming in the northeastern off-equatorial Pacific that promoted an increased meridional SST gradient. This highlights the importance of accurately reproducing TIW activity in ENSO simulation and the benefit of off-equatorial SST anomalies in the eastern Pacific as an independent precursor for ENSO predictions.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding authors: Dr. Wenjun Zhang, zhangwj@nuist.edu.cn; Dr. Fei-Fei Jin, jff@hawaii.edu
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