Instrusion of the potential vorticity in the upper troposferic over south tropical atlantic and its relation with precipitation over NE of Brazil / Intrusão de vorticidade potencial na alta troposfera sobre o Atlântico tropical sul e sua relação com a precipitação no NE do Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The Northeast Brazil (NEB) presents a great interannual variability of precipitation that can probably be explained by some atmospherics phenomenon of large scale. A system that can have some relationship with this variability is the intrusion event, characterised by Rossby wave breaking that provokes a connection between the tropical and extratropical region. This work has the objective to verify a relation between the precipitation over the north (NNE), east (ENE) and south (SNE) of NEB and the intrusion events over the South Atlantic (SA). The normalised deviation of the precipitation has significant correlation over the NNE (negative) and SNE (positive) with the intrusions. During the El Niño years several intrusion events occurred, while La Niña years ocurred less events. Analysing extremes years, 1985 (rainy year), 1983 and 1993 (dry years), it was found that in drier years more intrusions events occur, and the strengthening of cyclone in high levels was observed and consequently less precipitation occurs over NEB. In rainy years there are no intrusions events. To analyse how the intrusion event affect the precipitation over the NEB, two events characterised by isentropic potential vorticity of 2x10-6 K m2 s-1 kg-1 in 10° S were chosen. The intrusion event change the wind flux, composing a trough over the NEB. This trough generates cyclonic vorticity at high levels. Regions with cyclonic vorticity bring convergence in high levels and consequently subsidence. For this motive the intrusion event affects the precipitation over the NEB in a negative form.

ASSUNTO(S)

onda de rossby intrusion variação anual meteorology vorticidade annual variation meteorologia sinótica vorticity northest region (brazil) rossby wave intrusão região nordeste (brasil) meteorologia synoptic meteorology

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