@article{fdi:010074991,
  title = {{T}he dynamics of the {W}est {A}frican {M}onsoon. {P}art {V} : the detection and role of the dominant modes of convectively coupled equatorial rossby waves},
  author = {{J}anicot, {S}erge and {M}ounier, {F}. and {G}ervois, {S}. and {S}ultan, {B}enjamin and {K}iladis, {G}. {N}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}his study is the last in a series of papers addressing the dynamics of the {W}est {A}frican summer monsoon at intraseasonal time scales between 10 and 90 days. {T}he signals of convectively coupled equatorial {R}ossby ({ER}) waves within the summer {A}frican monsoon have been investigated after filtering {NOAA} outgoing longwave radiation ({OLR}) data within a box delineated by the dispersion curves of the theoretical {ER} waves. {T}wo families of waves have been detected in the 10-100-day periodicity band by performing a singular spectrum analysis on a regional index of {ER}-filtered {OLR}. {F}or each family the first {EOF} mode has been retained to focus on the main convective variability signal. {W}ithin the periodicity band of 30-100 days, an {ER} wave pattern with an approximate wavelength of 13 500 km has been depicted. {T}his {ER} wave links the {MJO} mode in the {I}ndian monsoon sector with the main mode of convective variability over {W}est and central {A}frica. {T}his confirms the investigations carried out in previous studies. {W}ithin the 10-30-day periodicity band, a separate {ER} wave pattern has been highlighted in the {A}frican monsoon system with an approximate wavelength of 7500 km, a phase speed of 6 m s(-1), and a period of 15 days. {T}he combined {OLR} and atmospheric circulation pattern looks like a combination of {ER} wave solutions with meridional wavenumbers of 1 and 2. {I}ts vertical baroclinic profile suggests that this wave is forced by the deep convective heating. {I}ts initiation in terms of {OLR} modulation is detected north of {L}ake {V}ictoria, extending northward and then propagating westward along the {S}ahel latitudes. {T}he {S}ahel mode identified in previous studies corresponds to the second main mode of convective variability within the 10-30-day periodicity band, and this has also been examined. {I}ts pattern and evolution look like the first-mode {ER} wave pattern and they are temporally correlated with a coefficient of +0.6. {A}bout one-third of the {S}ahel mode events are concomitant with an {ER} wave occurrence. {T}he main difference between these two signals consists of a stronger {OLR} and circulation modulation of the {S}ahel mode over {E}ast and central {A}frica. {T}hus, the {S}ahel mode occurrence and its westward propagation could be explained in part by atmospheric dynamics associated with the {ER} waves and in part by land surface interactions, as shown in other studies.},
  keywords = {{ZONE} {EQUATORIALE}},
  booktitle = {},
  journal = {{J}ournal of {C}limate},
  volume = {23},
  numero = {14},
  pages = {4005--4024},
  ISSN = {0894-8755},
  year = {2010},
  URL = {https://www.documentation.ird.fr/hor/fdi:010074991},
}