@article{fdi:010088813,
  title = {{T}ropical origins of the {P}acific meridional mode associated with the nonlinear interaction of {ENSO} with the annual cycle},
  author = {{J}iang, {F}. and {Z}hang, {W}. {J}. and {B}oucharel, {J}ulien and {J}in, {F}. {F}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {P}acific {M}eridional {M}ode ({PMM}) has long been associated with extra-tropical air-sea coupling processes, which are thought to influence the development of {E}l {N}ino-{S}outhern {O}scillation ({ENSO}). {H}ere we show that the {PMM} on seasonal to interannual timescales is closely associated with a newly proposed tropical mode known as the {ENSO} {C}ombination mode ({C}-mode), which arises from the nonlinear interaction between {ENSO} and the background annual cycle in the deep tropics. {T}he {PMM} exhibits a remarkable resemblance with the {C}-mode in atmospheric patterns, spectral characteristics, and local impacts. {B}ased on a simple {H}asselmann-type model, we further demonstrate that the {C}-mode-related atmospheric anomalies can effectively drive {PMM}-like sea surface temperature anomalies. {A}s the {C}-mode captures seasonally modulated {ENSO} characteristics, the seasonal-to-interannual {PMM} variability could naturally establish a connection with {ENSO}, thereby offering an alternative explanation for the observed relationship between {PMM} and {ENSO}. {P}revious studies demonstrated that the {P}acific {M}eridional {M}ode ({PMM}) is driven by the extratropical climate systems, which can impact the development of {E}l {N}ino-{S}outhern {O}scillation ({ENSO}) events in the tropics. {I}n our study, we establish a close connection between the {PMM} on seasonal-to-interannual timescales and a tropical atmospheric mode arising from the nonlinear interaction between {ENSO} and the background annual cycle (the {ENSO} {C}ombination mode, {C}-mode). {T}he {C}-mode closely resembles the {PMM} in terms of atmospheric patterns and spectral characteristics. {W}e further demonstrate that the {C}-mode could drive a {PMM}-like {SST} pattern in the tropical {P}acific. {C}onsequently, we suggest that the {PMM} on seasonal-to-interannual timescales has tropical origins, thereby offering an alternative explanation for the relationship between the conventional {PMM} index and the mature phase of {ENSO}. {T}he spatiotemporal features of {P}acific {M}eridional {M}ode ({PMM}) on seasonal-to-interannual timescales exhibit a remarkable resemblance with those of the tropical combination mode{C}-mode-related atmospheric anomalies are capable of inducing {PMM}-like sea surface temperature changes in the tropical {P}acific{E}l {N}ino-{S}outhern {O}scillation ({ENSO})'s interaction with the annual cycle manifests in {PMM}-related air-sea conditions, which explains the observed {ENSO}-{PMM} linkage},
  keywords = {{ENSO} ; {PMM} ; seasonal cycle ; {C}-mode ; {PACIFIQUE}},
  booktitle = {},
  journal = {{G}eophysical {R}esearch {L}etters},
  volume = {50},
  numero = {24},
  pages = {e2023{GL}106225 [10 ]},
  ISSN = {0094-8276},
  year = {2023},
  DOI = {10.1029/2023gl106225},
  URL = {https://www.documentation.ird.fr/hor/fdi:010088813},
}