@article{fdi:010084281,
  title = {{R}ecent changes in the atmospheric circulation patterns during the dry-to-wet transition season in {S}outh {T}ropical {S}outh {A}merica (1979-2020) : impacts on precipitation and fire season},
  author = {{E}spinoza, {J}. {C}. and {A}rias, {P}. {A}. and {M}oron, {V}. and {J}unquas, {C}l{\'e}mentine and {S}egura, {H}. and {S}ierra-{P}erez, {J}. {P}. and {W}ongchuig, {S}. and {C}ondom, {T}homas},
  editor = {},
  language = {{ENG}},
  abstract = {{W}e analyze the characteristics of atmospheric variations over tropical {S}outh {A}merica using the pattern recognition framework of weather typing or atmospheric circulation patterns ({CP}s). {D}uring 1979-2020, nine {CP}s are defined in the region, using a k-means algorithm based on daily unfiltered 850-h{P}a winds over 10 degrees {N}-30 degrees {S}, 90 degrees-30 degrees {W}. {CP}s are primarily interpreted as stages of the annual cycle of the low-level circulation. {W}e identified three "winter' {CP}s ({CP}7, {CP}8, and {CP}9), three "summer' {CP}s ({CP}3, {CP}4, and {CP}5), and three "transitional' {CP}s ({CP}1, {CP}2, and {CP}6). {S}ignificant long-term changes are detected during the dry-to-wet transition season ({J}uly-{O}ctober) over southern tropical {S}outh {A}merica ({STSA}). {O}ne of the wintertime patterns ({CP}9) increases from 20% in the 1980s to 35% in the last decade while the "transitional' {CP}2 decreases from 13% to 7%. {CP}9 is characterized by enhancement of the {S}outh {A}merican low-level jet and increasing atmospheric subsidence over {STSA}. {CP}2 is characterized by southerly cold-air incursions and anomalous convective activity over {STSA}. {T}he years characterized by high frequency of {CP}9 and low frequency of {CP}2 during the dry-to-wet transition season are associated with a delayed {S}outh {A}merican monsoon onset and anomalous dry conditions over {STSA}. {C}onsistently, a higher frequency of {CP}9 intensifies the fire season over {STSA} (1999-2020). {O}ver the {B}razilian states of {M}aranhao, {T}ocantins, {G}oias, and {S}ao {P}aulo, the seasonal frequency of {CP}9 explains around 35%-44% of the interannual variations of fire counts.},
  keywords = {{A}mazon region ; {S}outh{A}merica ; {A}tmospheric circulation ; {I}nterannual variability ; {S}ubseasonal variability ; {T}rends ; {BRESIL} ; {AMAZONIE} ; {ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{J}ournal of {C}limate},
  volume = {34},
  numero = {22},
  pages = {9025--9042},
  ISSN = {0894-8755},
  year = {2021},
  DOI = {10.1175/jcli-d-21-0303.1},
  URL = {https://www.documentation.ird.fr/hor/fdi:010084281},
}