@article{fdi:010054219,
  title = {{P}rocesses controlling the surface temperature signature of the {M}adden-{J}ulian {O}scillation in the thermocline ridge of the {I}ndian {O}cean},
  author = {{J}ayakumar, {A}. and {V}ialard, {J}{\'e}r{\^o}me and {L}engaigne, {M}atthieu and {G}nanaseelan, {C}. and {M}c{C}reary, {J}. {P}. and {K}umar, {B}. {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{D}uring boreal winter, there is a prominent maximum of intraseasonal sea-surface temperature ({SST}) variability associated with the {M}adden-{J}ulian {O}scillation ({MJO}) along a {T}hermocline {R}idge located in the southwestern {I}ndian {O}cean (5{A} degrees {S}-10{A} degrees {S}, 60{A} degrees {E}-90{A} degrees {E}; {TRIO} region). {T}here is an ongoing debate about the relative importance of air-sea heat fluxes and oceanic processes in driving this intraseasonal {SST} variability. {F}urthermore, various studies have suggested that interannual variability of the oceanic structure in the {TRIO} region could modulate the amplitude of the {MJO}-driven {SST} response. {I}n this study, we use observations and ocean general circulation model ({OGCM}) experiments to quantify these two effects over the 1997-2006 period. {O}bservational analysis indicates that {E}kman pumping does not contribute significantly (on average) to intraseasonal {SST} variability. {I}t is, however, difficult to quantify the relative contribution of net heat fluxes and entrainment to {SST} intraseasonal variability from observations alone. {W}e therefore use a suite of {OGCM} experiments to isolate the impacts of each process. {D}uring 1997-2006, wind stress contributed on average only about 20% of the intraseasonal {SST} variability (averaged over the {TRIO} region), while heat fluxes contributed about 70%, with forcing by shortwave radiation (75%) dominating the other flux components (25%). {T}his estimate is consistent with an independent air-sea flux product, which indicates that shortwave radiation contributes 68% of intraseasonal heat flux variability. {T}he time scale of the heat-flux perturbation, in addition to its amplitude, is also important in controlling the intraseasonal {SST} signature, with longer periods favouring a larger response. {T}here are also strong year-to-year variations in the respective role of heat fluxes and wind stress. {O}f the five strong cooling events identified in both observations and the model (two in 1999 and one in 2000, 2001 and 2002), intraseasonal-wind stress dominates the {SST} signature during 2001 and contributes significantly during 2000. {I}nterannual variations of the subsurface thermal structure associated with the {I}ndian {O}cean {D}ipole or {E}l {N}io/{L}a {N}ia events modulate the {MJO}-driven {SST} signature only moderately (by up to 30%), mainly by changing the temperature of water entrained into the mixed layer. {T}he primary factor that controls year-to-year changes in the amplitude of {TRIO}, intraseasonal {SST} anomalies is hence the characteristics of intraseasonal surface flux perturbations, rather than changes in the underlying oceanic state.},
  keywords = {{I}ntraseasonal variability ; {I}ndian {O}cean ; {M}adden-{J}ulian {O}scillation ; {T}hermocline ridge ; {M}ixed layer processes ; {I}nterannual variability},
  booktitle = {},
  journal = {{C}limate {D}ynamics},
  volume = {37},
  numero = {11-12},
  pages = {2217--2234},
  ISSN = {0930-7575},
  year = {2011},
  DOI = {10.1007/s00382-010-0953-5},
  URL = {https://www.documentation.ird.fr/hor/fdi:010054219},
}