@article{fdi:010053830,
  title = {{S}ensitivity of {ENSO} to stratification in a recharge-discharge conceptual model},
  author = {{T}hual, {S}. and {D}ewitte, {B}oris and {A}n, {S}. {I}. and {A}youb, {N}.},
  editor = {},
  language = {{ENG}},
  abstract = {{E}l {N}ino-{S}outhern {O}scillation ({ENSO}) is driven by large-scale ocean-atmosphere interactions in the equatorial {P}acific and is sensitive to change in the mean state. {W}hereas conceptual models of {ENSO} usually consider the depth of the thermocline to be influential on the stability of {ENSO}, the observed changes in the depth of the 20 degrees {C} isotherm are rather weak, on the order of approximately 5 m over the last decades. {C}onversely, change in stratification that affects both the intensity and sharpness of the thermocline can be pronounced. {H}ere, the two-strip conceptual model of {A}n and {J}in is extended to include three parameters (i.e., the contribution of the first three baroclinic modes) that account for the main characteristics of the mean thermocline vertical structure. {A} stability analysis of the model is carried out that indicates that the model sustains a lower {ENSO} mode when the high-order baroclinic modes ({M}2 and {M}3) are considered. {T}he sensitivity of the model solution to the coupling efficiency further indicates that, in the weak coupling regime, the model allows for several ocean basin modes at low frequency. {T}he latter can eventually merge into a low-frequency and unstable mode representative of {ENSO} as the coupling efficiency increases. {A}lso, higher baroclinic modes project more energy onto the ocean dynamics for the same input of wind forcing. {T}herefore, in this study's model, a shallower, yet more intense mean thermocline may still sustain a strong (i.e., unstable) and low-frequency {ENSO} mode. {S}ensitivity tests to the strength of the two dominant feedbacks (thermocline vs zonal advection) indicate that the presence of high-order baroclinic modes favors the bifurcation from a low-frequency regime to a higher-frequency regime when the zonal advective feedback is enhanced. {I}t is suggested that the proposed formalism can be used to interpret and measure the sensitivity of coupled general circulation models to climate change.},
  keywords = {{PACIFIQUE}},
  booktitle = {},
  journal = {{J}ournal of {C}limate},
  volume = {24},
  numero = {16},
  pages = {4332--4349},
  ISSN = {0894-8755},
  year = {2011},
  DOI = {10.1175/2011jcli4148.1},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053830},
}