@article{fdi:010089725,
  title = {{D}ynamical study of three {A}frican {E}asterly waves in september 2021},
  author = {{J}onville, {T}. and {F}lamant, {C}. and {L}avaysse, {C}hristophe},
  editor = {},
  language = {{ENG}},
  abstract = {{T}hree convectively active {A}frican easterly waves ({AEW}s) that propagated south of the {A}frican easterly jet were observed over the northeast {A}tlantic {O}cean in {S}eptember 2021. {T}heir evolution is studied using a suite of theoretical frameworks, as well as the {E}uropean {C}entre for {M}edium-range {W}eather {F}orecast reanalyses and satellite-derived brightness temperature observations. {T}he environment of these {AEW}s was sampled during the {C}loud-{A}tmospheric {D}ynamics-{D}ust {I}nteractions in {W}est {A}frica campaign near {C}ape {V}erde with the goal to assess their potential for developing into tropical cyclones. {W}e highlight the processes that inhibited the development of the first {AEW} (which evolved into tropical disturbance {P}ierre-{H}enri) and that played a role in the development of the later two into tropical storms {R}ose and {P}eter on {S}eptember 19, 2021. {T}he three {AEW}s developed a so-called "marsupial protective" pouch. {F}or {P}eter and {R}ose, the pouch was associated with a vertically aligned vortex at low levels and efficiently protected the convective systems inside from dry and dusty air intrusion. {T}he development of this low-level vortex is associated with an interaction with the monsoon trough for {R}ose and with a vorticity center associated with a wave propagating north of the {A}frican easterly jet ({AEJ}) in the case of {P}eter. {T}he presence of a dust flux toward the convective core near the surface is highlighted for {R}ose and {P}eter in spite of the presence of the protective marsupial pouch. {O}n the other hand, {P}ierre-{H}enri interacted positively with both the monsoon trough and an {AEW} north of the {AEJ} but failed to develop into a tropical cyclone. {T}he wave north of the {AEJ} brought {S}aharan air layer air masses inside the pouch that led to a drying of the circulation that may explain the decrease in convective activity. {W}e used different methods to analyse the processes that helped or inhibited the development of three {A}frican easterly waves ({AEW}s) into tropical cyclones. {A} wave pouch structure that protects a convective system moving with the wave is observed in the three cases and studied within the marsupial paradigm framework. {T}he development of an aligned vortex at low levels, either by interaction with the monsoon trough or between {AEW}s north and south of the {A}frican easterly jet, are highlighted. {I}n one case, the latter interaction caused the intrusion of dry air that might have inhibited cyclogenesis. image},
  keywords = {{A}frican easterly waves ; deep convection ; dust ; monsoon trough zone ; tropical cyclones ; tropical storms ; {AFRIQUE} {DE} {L}'{OUEST} ; {ATLANTIQUE} ; {SAHARA} ; {ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{Q}uarterly {J}ournal of the {R}oyal {M}eteorological {S}ociety},
  volume = {[{E}arly access]},
  numero = {},
  pages = {[21 ]},
  ISSN = {0035-9009},
  year = {2024},
  DOI = {10.1002/qj.4720},
  URL = {https://www.documentation.ird.fr/hor/fdi:010089725},
}