@article{fdi:010085011,
  title = {{N}onnormal multidecadal response of the thermohaline circulation induced by optimal surface salinity perturbations},
  author = {{S}evellec, {F}. and {H}uck, {T}. and {B}en {J}elloul, {M}. and {V}ialard, {J}{\'e}r{\^o}me},
  editor = {},
  language = {{ENG}},
  abstract = {{O}ptimal perturbations of sea surface salinity are obtained for an idealized {N}orth {A}tlantic basin using a 3{D} planetary geostrophic model-optimality is defined with respect to the intensity of the meridional overturning circulation. {B}oth optimal initial and stochastic perturbations are computed in two experiments corresponding to two different formulations of the surface boundary conditions: the first experiment uses mixed boundary conditions (i.e., restoring surface temperature and prescribed freshwater flux), whereas the second experiment uses flux boundary conditions for both temperature and salinity. {T}he latter reveals greater responses to both initial and stochastic perturbations that are related to the existence of a weakly damped oscillatory eigenmode of the {J}acobian matrix, the optimal perturbations being closely related to its bi-orthogonal. {T}he optimal initial perturbation induces a transient modification of the circulation after 24 yr. {T}he spectral response to the optimal stochastic perturbation reveals a strong peak at 35 yr, corresponding to the period of this oscillatory eigenmode. {T}his study provides an upper bound of the meridional overturning response at multidecadal time scales to freshwater flux perturbation: for typical amplitudes of {G}reat {S}alinity {A}nomalies, initial perturbations can alter the circulation by +2.25 {S}v (1 {S}v equivalent to 10(6) m(3) s(-1); i.e., 12.5% of the mean circulation) at most; stochastic perturbations with amplitudes typical of the interannual variability of the freshwater flux in midlatitudes induce a circulation variability with a standard deviation of 1 {S}v (i.e., 5.5% of the mean circulation) at most.},
  keywords = {},
  booktitle = {},
  journal = {{J}ournal of {P}hysical {O}ceanography},
  volume = {39},
  numero = {4},
  pages = {852--872},
  ISSN = {0022-3670},
  year = {2009},
  DOI = {10.1175/2008jpo3998.1},
  URL = {https://www.documentation.ird.fr/hor/fdi:010085011},
}