@article{fdi:010053594,
  title = {{S}outhern {H}emisphere extra-tropical forcing : a new paradigm for {E}l {N}ino-{S}outhern {O}scillation},
  author = {{T}erray, {P}ascal},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he main goal of this paper is to shed additional light on the reciprocal dynamical linkages between mid-latitude {S}outhern {H}emisphere climate and the {E}l {N}io-{S}outhern {O}scillation ({ENSO}) signal. {W}hile our analysis confirms that {ENSO} is a dominant source of interannual variability in the {S}outhern {H}emisphere, it is also suggested here that subtropical dipole variability in both the {S}outhern {I}ndian and {A}tlantic {O}ceans triggered by {S}outhern {H}emisphere mid-latitude variability may also provide a controlling influence on {ENSO} in the equatorial {P}acific. {T}his subtropical forcing operates through various coupled air-sea feedbacks involving the propagation of subtropical sea surface temperature ({SST}) anomalies into the deep tropics of the {A}tlantic and {I}ndian {O}ceans from boreal winter to boreal spring and a subsequent dynamical atmospheric response to these {SST} anomalies linking the three tropical basins at the beginning of the boreal spring. {T}his atmospheric response is characterized by a significant weakening of the equatorial {A}tlantic and {I}ndian {I}nter-{T}ropical {C}onvergence {Z}one ({ITCZ}). {T}his weakened {ITCZ} forces an equatorial "cold {K}elvin wave" response in the middle to upper troposphere that extends eastward from the heat sink regions into the western {P}acific. {B}y modulating the vertical temperature gradient and the stability of the atmosphere over the equatorial western {P}acific {O}cean, this {K}elvin wave response promotes persistent zonal wind and convective anomalies over the western equatorial {P}acific, which may trigger {E}l {N}io onset at the end of the boreal winter. {T}hese different processes explain why {S}outh {A}tlantic and {I}ndian subtropical dipole time series indices are highly significant precursors of the {N}io34 {SST} index several months in advance before the {E}l {N}io onset in the equatorial {P}acific. {T}his study illustrates that the atmospheric internal variability in the mid-latitudes of the {S}outhern {H}emisphere may significantly influence {ENSO} variability. {H}owever, this surprising relationship is observed only during recent decades, after the so-called 1976/1977 climate regime shift, suggesting a possible linkage with global warming or decadal fluctuations of the climate system.},
  keywords = {{ENSO} ; {S}outhern {H}emisphere ; {L}ong-range predictability ; {O}cean-atmosphere ; interactions},
  booktitle = {},
  journal = {{C}limate {D}ynamics},
  volume = {36},
  numero = {11-12},
  pages = {2171--2199},
  ISSN = {0930-7575},
  year = {2011},
  DOI = {10.1007/s00382-010-0825-z},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053594},
}