@article{PAR00004450,
  title = {{A}tmospheric and upper ocean environments of {S}outhern {O}cean polar mesocyclones in the transition season months and associations with teleconnections},
  author = {{C}laud, {C}. and {C}arleton, {A}. {M}. and {D}uchiron, {B}. and {T}erray, {P}ascal},
  editor = {},
  language = {{ENG}},
  abstract = {{O}ver middle and higher latitudes of the {S}outhern {H}emisphere, intense mesoscale cyclonic vortices that develop in cold-air outbreaks (cold-air mesocyclones) occur frequently during transition season months. {I}n this study, previously published mesocyclone inventories for {M}arch-{A}pril and {O}ctober-{N}ovember are compared to atmospheric and upper ocean variables pertinent to mesocyclogenesis, as provided by reanalyses. {T}his procedure allows the determination of the large-scale environments favorable for mesocyclone occurrence: low midtropospheric temperatures, greater sea ice extent, and large positive differences in the sea surface temperature minus low-altitude air temperature, the latter coinciding with enhanced low-level winds having a southerly component. {W}e then evaluate the associations between polar mesocyclone formation and dominant patterns of low-frequency variability in the atmospheric circulation: the {E}l {N}ino-{S}outhern {O}scillation ({ENSO}), the {S}outhern {A}nnular {M}ode ({SAM}), and the {T}rans-{P}olar {I}ndex ({TPI}). {O}ur results suggest that in spring, the intrahemispheric variability in mesocyclogenesis is dominated by {ENSO}. {I}n autumn, the influences of {ENSO}, {SAM}, and {TPI} on mesocyclone activity are about equal, although the response differs regionally. {M}oreover, teleconnections' effects on mesocyclone activity are somewhat reduced compared to that in spring. {I}n both seasons, the phase of the semiannual oscillation modulates the associations with mesocyclones by influencing the latitude of the circumpolar trough and the amount of cyclonic activity over the {S}outhern {O}cean. {T}hese associations likely result from the displacement of the storm track between opposite phases of a given teleconnection and its position relative to the sea ice edge.},
  keywords = {},
  booktitle = {},
  journal = {{J}ournal of {G}eophysical {R}esearch-{A}tmospheres},
  volume = {114},
  numero = {},
  pages = {{D}23104},
  ISSN = {0148-0227},
  year = {2009},
  DOI = {10.1029/2009jd011995},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00004450},
}