Brazilian Northeast Jet Stream: frequency, wind speed and direction

摘要

The Brazilian Northeast Jet Stream (BNEJS) was analysed over 16years (1994-2009) using reanalysis data from the National Center for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR). With a wind speed higher than 30ms(-1), the BNEJS was observed on average for 69daysyear(-1), and reached 114days in 2003. More frequently, these jet streams were observed during the rainy season (9daysmonth(-1), on average), and rarely between February and April (2daysmonth(-1), on average). The study found that the BNEJS, with a minimum speed limit of 20ms(-1), occurred very often (it was detected almost every day). The average wind speed of the BNEJS was 37ms(-1), and reached a maximum of 64ms(-1). The directions of the BNEJS were identified to be more often from the northwest and the southwest, and were rarely found occurring from the north. That from the northwest occurred more frequently in winter and autumn (288 and 172days, respectively). The BNEJS's direction from the southeast has a similar frequency during both spring and summer (64 and 63days, respectively).