@article{fdi:010088587,
  title = {{T}he effect of {I}ndian {O}cean temperature on the {P}acific trade winds and {ENSO}},
  author = {{F}erster, {B}. {S}. and {F}edorov, {A}. {V}. and {G}uilyardi, {E}. and {M}ignot, {J}uliette},
  editor = {},
  language = {{ENG}},
  abstract = {{A} notable shift in the {E}l {N}ino-{S}outhern {O}scillation ({ENSO}) has been observed in the early 21st century, characterized by an increased prevalence of {C}entral {P}acific ({CP}) events and strengthened {P}acific trade winds. {T}his shift may be attributed to the warming tropical {I}ndian {O}cean ({TIO}). {T}o investigate this, we conduct perturbation experiments using the {I}nsitut {P}ierre {S}imon {L}aplace climate model and nudge {TIO} surface temperatures to induce warming or cooling effects. {O}ur findings reveal that {TIO} warming (or cooling) leads to amplified (weakened) mean trade winds and surface warming (cooling) in the {P}acific region. {S}urprisingly, {ENSO} variability increases in both {TIO} cooling and warming scenarios. {T}his result is linked to stronger positive feedbacks and a less stable {B}jerknes index for either {TIO} forcing. {A}dditionally, we find that {TIO} warming leads to more frequent {CP} events, meridional widening of wind anomalies, and broadening of the {ENSO} power spectrum toward lower frequencies. {T}he dominant mode of interannual climate variability, the {E}l {N}ino-{S}outhern {O}scillation ({ENSO}), has visibly changed in the past three decades, with maximum sea surface temperature ({SST}) anomalies during {E}l {N}ino events occurring in the {C}entral {P}acific ({CP}) rather than in the {E}astern {P}acific and having weaker magnitudes. {R}ecent studies suggest that the observed stronger {P}acific trade winds could have contributed to this shift. {O}ne possible mechanism driving such changes is the enhanced warming trends in the tropical {I}ndian {O}cean ({TIO}) relative to the rest of the tropics. {H}ere, we conduct sensitivity experiments to investigate the effect of {TIO} {SST} on the {P}acific. {O}ur experiments with a climate model indicate that the {P}acific trade winds change proportionally to the imposed forcing, with stronger trades corresponding to a warmer {TIO}. {W}e find that {ENSO} variability increases strongly in the {TIO} cooling experiments, driven by weaker trade winds associated with {TIO} cooling. {I}n the {TIO} warming experiments we find a shift toward {CP}-like events; however, we also observe a modest {ENSO} strengthening, which can be attributed to stronger positive feedbacks resulting from the remotely induced warming of the {P}acific. {I}nitial response to {I}ndian {O}cean warming (cooling) produces {L}a {N}ina-like ({E}l {N}ino-line) conditions in the tropical {P}acific{E}quilibrium response to {I}ndian {O}cean warming (cooling) shows stronger (weaker) {P}acific trade winds but warmer (colder) ocean temperatures{B}oth warming and cooling of the {I}ndian {O}cean result in a stronger {E}l {N}ino-{S}outhern {O}scillation due to greater positive feedbacks in the {B}jerknes stability index},
  keywords = {{ENSO} ; {OCEAN} {INDIEN} ; {PACIFIQUE}},
  booktitle = {},
  journal = {{G}eophysical {R}esearch {L}etters},
  volume = {50},
  numero = {20},
  pages = {e2023{GL}103230 [11 p.]},
  ISSN = {0094-8276},
  year = {2023},
  DOI = {10.1029/2023gl103230},
  URL = {https://www.documentation.ird.fr/hor/fdi:010088587},
}