@article{fdi:010090690,
  title = {{W}hy do oceanic nonlinearities contribute only weakly to extreme {E}l {N}iño events ?},
  author = {{L}iu, {F}. {Y}. and {V}ialard, {J}{\'e}r{\^o}me and {F}edorov, {A}. {V}. and Éth{\'e}, {C}. and {P}erson, {R}enaud and {Z}hang, {W}. {J}. and {L}engaigne, {M}atthieu},
  editor = {},
  language = {{ENG}},
  abstract = {{E}xtreme {E}l {N}ino events have outsized global impacts and control the {E}l {N}ino {S}outhern {O}scillation ({ENSO}) warm/cold phases asymmetries. {Y}et, a consensus regarding the relative contributions of atmospheric and oceanic nonlinearities to their genesis remains elusive. {H}ere, we isolate the contribution of oceanic nonlinearities by conducting paired experiments forced with opposite wind stress anomalies in an oceanic general circulation model, which realistically simulates extreme {E}l {N}ino events and oceanic nonlinearities thought to contribute to {ENSO} skewness ({T}ropical {I}nstability {W}aves ({TIW}s), {N}onlinear {D}ynamical {H}eating ({NDH})). {O}ur findings indicate a weak contribution of oceanic nonlinearities to extreme {E}l {N}ino events in the eastern {P}acific, owing to compensatory effects between lateral ({NDH} and {TIW}s) and vertical processes. {T}hese results hold across different vertical mixing schemes and modifications of the upper-ocean heat budget mixed layer criterion. {O}ur study reinforces previous research underscoring the pivotal role of atmospheric nonlinearities in shaping extreme {E}l {N}i & ntilde;o events. {T}he {E}l {N}i & ntilde;o-{S}outhern {O}scillation ({ENSO}) is the primary driver of year-to-year climate variations in the tropics and beyond. {O}riginating from air-sea interactions in the tropical {P}acific, {ENSO} oscillates between warm ({E}l {N}ino) and cold ({L}a {N}ina) phases, modulating sea surface temperature in the central and eastern equatorial {P}acific. {O}ccasionally, {E}l {N}ino events intensify into "super" {E}l {N}ino events, causing widespread impacts globally. {U}tilizing a state-of-the-art oceanic model, our research challenges previous results suggesting a strong oceanic contribution to the amplitude difference between "normal" and "super" {E}l {N}ino events. {I}nstead, our findings reveal that potential oceanic influences on "super" {E}l {N}ino events tend to offset each other. {T}his is consistent with recent research highlighting the crucial role of atmospheric processes in the transformation from a "normal" to a "super" {E}l {N}ino. {A} state-of-the-art ocean model reproduces extreme {E}l {N}ino events and the corresponding nonlinear oceanic processes realistically {C}ontributions from oceanic nonlinearities are isolated using paired simulations forced by opposite wind stress anomalies {E}ffects of oceanic nonlinearities on extreme {E}l {N}ino events are small, due to compensation between lateral and vertical processes},
  keywords = {extreme {E}l {N}ino ; {ENSO} asymmetries ; oceanic nonlinearities ; {PACIFIQUE}},
  booktitle = {},
  journal = {{G}eophysical {R}esearch {L}etters},
  volume = {51},
  numero = {11},
  pages = {e2024{GL}108813 [10 ]},
  ISSN = {0094-8276},
  year = {2024},
  DOI = {10.1029/2024gl108813},
  URL = {https://www.documentation.ird.fr/hor/fdi:010090690},
}