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Impact of high potential vorticity intrusions into the tropical upper troposphere in South Atlantic on precipitation over northeast Brazil
Author(s) -
Rao V. Brahmananda,
Franchito Sergio H.,
Barbosa Tatiane Felinto
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl027873
Subject(s) - troposphere , westerlies , climatology , potential vorticity , precipitation , vorticity , geology , atmospheric sciences , vortex , environmental science , geography , meteorology
Interannual variations of high potential vorticity intrusions at 10°S in the upper troposphere during NDJFM are shown to be negatively correlated with rainfall over northern northeast Brazil (NEB). That is, higher intrusions associated with stronger equatorial westerlies may provoke droughts. Higher intrusions lead to the formation of an anomalous cyclonic vortex over NEB, which causes convergence in the upper troposphere and sinking motion at lower levels. The number of intrusions in NDJFM has highest correlation, significant at 99% confidence level, with the rainfall of the principal rainy season in FMAM.