@article{fdi:010083089,
  title = {{I}mplication of the {M}adden-{J}ulian {O}scillation in the 40-day variability of the {W}est {A}frican {M}onsoon},
  author = {{P}ohl, {B}. and {J}anicot, {S}erge and {F}ontaine, {B}. and {M}arteau, {R}.},
  editor = {},
  language = {{ENG}},
  abstract = {{M}adden-{J}ulian oscillations ({MJO}s) are extracted over the {I}ndo-{P}acific basin using a local mode analysis. {T}he convective perturbations are then projected over a larger domain to evaluate their remote consequences over the {W}est {A}frican monsoon ({WAM}) intraseasonal variability. {R}ather weak (4-6 {W} m 22) convective fluctuations occurring in phase with those over the southern {I}ndian basin are found over {A}frica, confirming the results of {M}atthews. {I}n reverse, 40-day fluctuations in the {WAM}, similarly detected and projected over a widened area, demonstrate that a large majority of these events are embedded in the larger-scale patterns of the {MJO}. {T}he regional amplitude of intraseasonal perturbations of the {W}est {A}frican convection is not statistically associated with the amplitude of the {MJO} over the {I}ndian basin but is instead closely related to background vertical velocity anomalies over {A}frica, possibly embedded in changes in the regional {W}alker-type circulation. {S}ubsiding motion over {A}frica is recorded during the most energetic convective perturbations in the {WAM}. {C}omposites analyses over the {MJO} life cycle, as depicted by the real-time daily indices developed by {W}heeler and {H}endon, show that positive outgoing longwave radiation ({OLR}) anomalies during the dry phase are of larger amplitude and spatially more coherent than negative anomalies during the wet phase, especially over the {S}ahel region. {O}ver {W}est {A}frica, the phase of suppressed convection is thus of greater importance for the region than the phase of enhanced convection. {R}ain gauge records fully confirm these results. {T}he {MJO} appears to be significantly involved in the occurrences of dry spells during the monsoon over the {S}ahel, whereas large-scale convective clusters are only restricted to the equatorial latitudes and thus affect the {G}uinean belt, which experiences its short dry season at this time of the year.},
  keywords = {{SAHEL}},
  booktitle = {},
  journal = {{J}ournal of {C}limate},
  volume = {22},
  numero = {13},
  pages = {3769--3785},
  ISSN = {0894-8755},
  year = {2009},
  DOI = {10.1175/2009jcli2805.1},
  URL = {https://www.documentation.ird.fr/hor/fdi:010083089},
}