@article{fdi:010063934,
  title = {{O}ceanic factors controlling the {I}ndian summer monsoon onset in a coupled model},
  author = {{P}rodhomme, {C}. and {T}erray, {P}ascal and {M}asson, {S}. and {B}oschat, {G}. and {I}zumo, {T}akeshi},
  editor = {},
  language = {{ENG}},
  abstract = {{D}espite huge socio-economical impacts, the predictability of the {I}ndian summer monsoon ({ISM}) onset remains drastically limited by the inability of both current forced and coupled models to reproduce a realistic monsoon seasonal cycle. {I}n the {SINTEX}-{F}2 coupled model, the mean {ISM} onset estimated with rainfall or thermo-dynamical indices is delayed by approximately 13 days, but it occurs 6 days early in the atmosphere-only component of the coupled model. {T}his 19 days lag between atmospheric-only and coupled runs, which is well above the observed standard-deviation of the {ISM} onset (10 days in the observations), suggests a crucial role of the coupling, including {S}ea {S}urface {T}emperatures ({SST}) biases, on the delayed mean onset in the coupled model. {O}n the other hand, the key-factors governing the interannual variability of the {ISM} onset date are also fundamentally different in the atmospheric and coupled experiments and highlight the importance of {E}l {N}io-{S}outhern {O}scillation ({ENSO}) and ocean-atmosphere coupling for a realistic simulation of the variability of the {ISM} onset date. {A}t both interannual and seasonal timescales, we demonstrate the importance of the meridional gradients of tropospheric temperature, moisture and vertical shear of zonal wind in the {I}ndian {O}cean for a realistic {ISM} onset simulation. {T}aking into account that the tropical tropospheric temperature and the vertical shear are not only controlled by local processes, but also by large-scale processes, we need to examine not only the {I}ndian {O}cean {SST} biases, but also those in others tropical basins in order to understand the delay of the mean onset date in the coupled model. {D}uring {A}pril and {M}ay, the main tropical {SST} biases in the coupled model are a strong warm bias in the {I}ndian, {P}acific and {A}tlantic {O}ceans, associated with an important excess of equatorial precipitations, and thus a warmer equatorial free troposphere. {I}n order to identify the keys tropical {SST} regions influencing the mean {ISM} onset date, sensitivity coupled experiments have been performed. {I}n these experiments, the {SST} is corrected separately in each tropical basin. {T}he correction of {SST} biases in the tropical {I}ndian and {A}tlantic oceans only slightly improves the onset date in the coupled model and produces "{E}l {N}io-like" changes in the tropical {P}acific. {C}onversely, the correction of the {P}acific {SST} biases advances the onset date by 9 days compared to the control coupled run. {T}hese results suggest that, while the correction of {I}ndian {SST} biases improves the rainfall spatial distribution, the delayed mean {ISM} onset date is mainly control by the tropical {P}acific {O}cean {SST} biases.},
  keywords = {{I}ndian summer monsoon ; {M}onsoon onset ; {C}oupled climate model ; {M}odel ; systematic errors ; {O}cean atmosphere interaction ; {I}nterannual variability ; {ENSO} ; {INDE} ; {OCEAN} {INDIEN} ; {PACIFIQUE} ; {ATLANTIQUE}},
  booktitle = {},
  journal = {{C}limate {D}ynamics},
  volume = {44},
  numero = {3-4},
  pages = {977--1002},
  ISSN = {0930-7575},
  year = {2015},
  DOI = {10.1007/s00382-014-2200-y},
  URL = {https://www.documentation.ird.fr/hor/fdi:010063934},
}